/* =========================================================
   Wiki Flashcards — design tokens
   Surfaces/text/type: dong-ui aliases + mint accent
   ========================================================= */

:root {
  /* Surfaces, type, and accent follow the shell kit. */
  --bg: var(--dx-bg);
  --bg-soft: var(--dx-card-solid);
  --bg-mid: var(--dx-card-solid);
  --bg-raised: var(--dx-card);
  --bg-card: var(--dx-card);
  --bg-elevated: var(--dx-card-solid);
  --border: var(--dx-border);
  --border-soft: var(--dx-border);
  --shadow: var(--dx-shadow);
  --max: 960px;

  /* Text */
  --text: var(--dx-text);
  --text-dim: var(--dx-muted);
  --text-mute: var(--dx-muted);

  /* Accent */
  --accent: var(--dx-accent);
  --accent-soft: var(--dx-accent-soft);
  --accent-border: var(--dx-border);
  --accent-ink: var(--dx-accent-fg);

  /* Semantic — deepened for light backgrounds */
  --green: #15803d;
  --green-soft: rgba(21, 128, 61, 0.14);
  --red: #b42318;
  --red-soft: rgba(180, 35, 24, 0.14);
  --amber: #9a6b00;
  --amber-soft: rgba(154, 107, 0, 0.14);
  --yt: #c62828;
  --hl-ink: #06221f;

  /* Type */
  --font-ui: var(--dx-font);
  --font-display: var(--dx-font);

  /* Shape & motion */
  --radius: var(--dx-radius);
  --radius-sm: var(--dx-radius-sm);
  --radius-card: var(--dx-radius);
  --radius-pill: 999px;
  --shadow-card: var(--dx-shadow);
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-spring: cubic-bezier(0.34, 1.4, 0.64, 1);
  --dur-fast: 160ms;
  --dur: 280ms;
  --dur-slow: 480ms;

  font-size: 16px;
}

html.dark {
  --bg: var(--dx-bg);
  --bg-soft: var(--dx-card-solid);
  --bg-mid: var(--dx-card-solid);
  --bg-raised: var(--dx-card);
  --bg-card: var(--dx-card);
  --bg-elevated: var(--dx-card-solid);
  --border: var(--dx-border);
  --shadow: var(--dx-shadow);
  --border-soft: var(--dx-border);
  --text: var(--dx-text);
  --text-dim: var(--dx-muted);
  --text-mute: var(--dx-muted);
  --accent: var(--dx-accent);
  --accent-soft: var(--dx-accent-soft);
  --accent-border: var(--dx-border);
  --accent-ink: var(--dx-accent-fg);
  --green: #4ade80;
  --green-soft: rgba(74, 222, 128, 0.14);
  --red: #f07178;
  --red-soft: rgba(240, 113, 120, 0.14);
  --amber: #e8b84a;
  --amber-soft: rgba(232, 184, 74, 0.14);
  --yt: #ff4444;
  --hl-ink: #c8fff6;
  --shadow-card: var(--dx-shadow);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html, body {
  height: 100%;
  min-height: 100%;
  margin: 0;
  color: var(--dx-text);
  font-family: var(--dx-font);
  font-optical-sizing: auto;
  -webkit-font-smoothing: antialiased;
  -webkit-tap-highlight-color: transparent;
  background-color: transparent;
  background-image: none;
}
html { background-color: var(--dx-bg); }
body.dx { overflow-x: clip; }

#app {
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
  height: 100dvh;
  max-width: min(var(--max), 100%);
  margin: 0 auto;
  position: relative;
  background: transparent;
}

.skip-link {
  position: fixed;
  top: 0.5rem;
  left: 0.5rem;
  z-index: 100;
  transform: translateY(-160%);
  border-radius: 8px;
  background: var(--text);
  color: var(--bg);
  padding: 0.65rem 0.85rem;
  min-height: 44px;
  font-weight: 700;
}
.skip-link:focus { transform: translateY(0); }

.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

/* ---------- Top bar ---------- */
#topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 56px;
  min-width: 0;
  padding: 6px max(12px, env(safe-area-inset-right)) 6px max(12px, env(safe-area-inset-left));
  padding-top: max(6px, env(safe-area-inset-top));
  background: var(--dx-header);
  backdrop-filter: blur(var(--dx-blur)) saturate(1.4);
  -webkit-backdrop-filter: blur(var(--dx-blur)) saturate(1.4);
  border-bottom: 1px solid var(--dx-border);
  color: var(--dx-text);
}
#topbar-title,
#topbar h1 {
  font-family: var(--dx-font);
  color: var(--dx-text);
  margin: 0;
  font-size: 1.05rem;
  font-weight: 700;
  flex: 1 1 auto;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  letter-spacing: -0.02em;
  line-height: 1.2;
}
#topbar-title.hidden { display: none; }
#topbar-status {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  justify-content: center;
  min-width: 0;
  max-width: 46%;
  gap: 1px;
  flex: 0 1 auto;
}
#topbar-meta:empty { display: none; }
#topbar-meta,
#sync-label {
  max-width: 100%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 0.72rem;
  line-height: 1.2;
  color: var(--text-dim);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}
#connect {
  flex-shrink: 0;
  padding: 0.55rem 0.85rem 0;
}
#connect[hidden] { display: none; }
#btn-connect {
  width: 100%;
  min-height: 44px;
  border-radius: var(--dx-radius-sm);
  border: 1px solid var(--dx-border);
  background: var(--dx-card);
  color: var(--dx-text);
  font: 600 0.92rem/1 var(--dx-font);
  cursor: pointer;
}
#btn-connect:active { transform: scale(0.99); }
#topbar .dong-theme-toggle {
  position: static;
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  min-width: 44px;
  min-height: 44px;
  border: 0;
  background: transparent;
  box-shadow: none;
}
#topbar .dong-theme-toggle__track {
  width: 44px;
  height: 28px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: color-mix(in srgb, var(--bg-raised) 88%, transparent);
  box-shadow: 0 1px 8px rgba(20, 18, 12, 0.08);
}
.icon-btn {
  background: var(--bg-raised);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: var(--radius-sm);
  width: 44px;
  height: 44px;
  font-size: 1.15rem;
  cursor: pointer;
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out), transform var(--dur-fast) var(--ease-out);
}
.icon-btn:hover { background: var(--bg-elevated); }
.icon-btn:active { transform: scale(0.96); }
.hidden { display: none !important; }

/* ---------- Main ---------- */
#view-root {
  flex: 1;
  width: 100%;
  overflow-y: auto;
  padding: 1rem 1rem calc(6rem + env(safe-area-inset-bottom));
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}
#loading {
  color: var(--text-dim);
  text-align: center;
  padding: 56px 0;
  font-weight: 500;
  letter-spacing: 0.02em;
}

/* ---------- Tab bar ---------- */
#tabbar {
  position: fixed;
  left: 50%;
  bottom: 0;
  z-index: 25;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  width: min(100%, var(--max));
  transform: translateX(-50%);
  border-top: 1px solid var(--dx-border);
  background: var(--dx-header);
  box-shadow: var(--dx-shadow);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  padding: 0.25rem 0.5rem env(safe-area-inset-bottom);
}
.tab,
.nav-tab {
  position: relative;
  display: flex;
  min-height: 58px;
  min-width: 44px;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 0.15rem;
  border: 0;
  background: transparent;
  color: var(--text-mute);
  font: inherit;
  font-family: var(--font-ui);
  font-size: 0.7rem;
  font-weight: 650;
  letter-spacing: 0.02em;
  cursor: pointer;
}
.tab::before,
.nav-tab::before {
  content: "";
  position: absolute;
  top: -0.25rem;
  width: 2rem;
  height: 3px;
  border-radius: 0 0 3px 3px;
  background: var(--accent);
  opacity: 0;
  transform: scaleX(0);
  transition: opacity 0.18s ease, transform 0.18s ease;
}
.tab.active,
.nav-tab.active {
  color: var(--accent);
}
.tab.active::before,
.nav-tab.active::before {
  opacity: 1;
  transform: scaleX(1);
}
.tab-icon,
.nav-icon {
  font-size: 1.25rem;
  line-height: 1;
}

/* ---------- Panels ---------- */
.panel {
  background: var(--dx-card);
  border: 1px solid var(--dx-border);
  border-radius: var(--dx-radius);
  padding: 16px;
  margin-bottom: 12px;
  box-shadow: var(--dx-shadow);
  color: var(--dx-text);
}

/* ---------- Insights-aligned dashboard language ---------- */
.eyebrow {
  display: block;
  color: var(--text-mute);
  font-size: 0.68rem;
  font-weight: 750;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}
.learning-hero {
  border: 1px solid var(--dx-border);
  border-radius: var(--dx-radius);
  background: var(--dx-card);
  box-shadow: var(--dx-shadow);
  padding: 1.2rem;
  margin-bottom: 0.75rem;
}
.hero-topline,
.section-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.hero-xp {
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 800;
}
.learning-hero h2,
.section-heading h2 {
  margin: 0;
  color: var(--text);
  letter-spacing: -0.025em;
}
.learning-hero h2 {
  margin: 0.35rem 0 0.85rem;
  font-size: clamp(1.25rem, 4.5vw, 1.75rem);
  font-weight: 750;
}
.hero-subtext {
  margin: 0.55rem 0 0;
  color: var(--text-mute);
  font-size: 0.78rem;
  font-weight: 600;
}
.status-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.45rem;
  margin-top: 1rem;
}
.status-stats > * {
  min-width: 0;
  min-height: 62px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--bg);
  color: var(--text);
  font: inherit;
  text-align: center;
  padding: 10px 6px;
}
.status-stats strong {
  display: block;
  font-size: 1.2rem;
  line-height: 1.1;
}
.status-stats span {
  display: block;
  margin-top: 0.25rem;
  color: var(--text-mute);
  font-size: 0.68rem;
  font-weight: 600;
}
.status-stats > button {
  cursor: pointer;
}
.goal-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0.65rem 0 0.4rem;
}
.goal-chip {
  background: var(--bg-raised);
  border: 1px solid var(--border);
  color: var(--text-dim);
  border-radius: var(--radius-pill);
  padding: 0.45rem 0.85rem;
  min-height: 44px;
  font: inherit;
  font-size: 0.72rem;
  font-weight: 650;
  cursor: pointer;
}
.goal-chip.active {
  background: var(--accent);
  color: var(--accent-ink);
  border-color: var(--accent);
  font-weight: 750;
}
.goal-track {
  height: 4px;
  margin-top: 0.5rem;
  background: color-mix(in srgb, var(--border) 75%, var(--bg));
  border-radius: var(--radius-pill);
  overflow: hidden;
}
.srs-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.45rem;
  margin-top: 1rem;
}
.srs-grid > * {
  min-width: 0;
  min-height: 62px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--bg);
  color: var(--text);
  font: inherit;
  text-align: center;
  padding: 10px 4px;
}
.srs-grid strong {
  display: block;
  font-size: 1.2rem;
  line-height: 1.1;
}
.srs-grid span {
  display: block;
  margin-top: 0.25rem;
  color: var(--text-mute);
  font-size: 0.62rem;
  font-weight: 600;
}
.fluent-chip {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  margin: 0 8px 8px 0;
  padding: 0.45rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
  background: var(--bg-raised);
  color: var(--text);
  font: inherit;
  font-size: 0.8rem;
  font-weight: 650;
  cursor: pointer;
}
.primary-action {
  display: flex;
  width: 100%;
  min-height: 68px;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.5rem;
  padding: 0.9rem 1rem;
  border: 0;
  border-radius: var(--radius);
  background: var(--dx-accent);
  box-shadow: var(--dx-shadow);
  color: var(--dx-accent-fg);
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: transform var(--dur-fast) var(--ease-out), box-shadow var(--dur-fast) var(--ease-out), opacity var(--dur-fast);
}
.primary-action:hover { box-shadow: 0 10px 26px rgba(62, 207, 191, 0.34); }
.primary-action:active { transform: scale(0.985); }
.primary-action small {
  display: block;
  margin-bottom: 0.2rem;
  font-size: 0.72rem;
  font-weight: 650;
  opacity: 0.85;
}
.primary-action strong {
  display: -webkit-box;
  overflow: hidden;
  font-size: 0.95rem;
  line-height: 1.35;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 2;
}
.primary-arrow {
  flex-shrink: 0;
  font-size: 1.4rem;
}
.primary-action:disabled {
  opacity: 0.42;
  cursor: default;
  box-shadow: none;
  transform: none;
}
.home-section { margin: 0 0 1.6rem; }
.section-heading { margin: 0 0 0.7rem; }
.section-heading h2 {
  margin-top: 0.15rem;
  font-size: 1.08rem;
  font-weight: 750;
}

.level-card,
.milestone-card,
.next-badge {
  border-radius: var(--radius);
}
.level-card {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin-bottom: 0.75rem;
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: calc(var(--radius-card) + 4px);
  background: var(--dx-card);
  box-shadow: var(--dx-shadow);
}
.level-orb {
  display: grid;
  width: 58px;
  height: 58px;
  flex-shrink: 0;
  place-items: center;
  border: 5px solid var(--accent);
  border-radius: 50%;
  background: var(--bg-raised);
  color: var(--accent);
  font-size: 1.25rem;
  font-weight: 850;
  box-shadow: 0 5px 18px rgba(20, 18, 12, 0.09);
}
.level-main { min-width: 0; flex: 1; }
.level-main h2,
.milestone-card h2,
.next-badge h2 {
  margin: 0.1rem 0 0;
  color: var(--text);
  font-size: 1.1rem;
  letter-spacing: -0.025em;
}
.milestone-card h2,
.next-badge h2 { font-size: 0.95rem; }
.level-main p {
  margin: 0.2rem 0 0.55rem;
  color: var(--text-mute);
  font-size: 0.7rem;
}
.level-card > strong {
  align-self: flex-start;
  color: var(--accent);
  font-size: 0.75rem;
  white-space: nowrap;
}
.milestone-card,
.next-badge {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  margin-bottom: 1.5rem;
  padding: 0.9rem;
  border: 1px solid var(--dx-border);
  border-radius: var(--dx-radius);
  background: var(--dx-card);
  color: var(--dx-text);
}
.milestone-card { margin-bottom: 0.75rem; }
button.milestone-card {
  width: 100%;
  text-align: left;
  font: inherit;
  color: inherit;
  cursor: pointer;
}
.milestone-card > div:nth-child(2),
.next-badge > div { min-width: 0; flex: 1; }
.milestone-card p,
.next-badge p {
  margin: 0.2rem 0 0;
  color: var(--text-dim);
  font-size: 0.76rem;
}
.milestone-icon {
  display: grid;
  width: 42px;
  height: 42px;
  flex-shrink: 0;
  place-items: center;
  border-radius: 50%;
  background: var(--bg-raised);
  color: var(--accent);
  font-size: 1rem;
  font-weight: 850;
  box-shadow: 0 4px 14px rgba(20, 18, 12, 0.08);
}
.milestone-card > button {
  width: 44px;
  height: 44px;
  flex-shrink: 0;
  border: 0;
  border-radius: 50%;
  background: transparent;
  color: var(--text);
  font-size: 1.4rem;
  cursor: pointer;
}
.progress-stat-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.55rem;
  margin-bottom: 0.75rem;
}
.progress-stat-grid > * {
  display: flex;
  min-width: 0;
  min-height: 74px;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  padding: 0.5rem;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--bg);
  color: var(--text);
  font: inherit;
  text-align: center;
}
.progress-stat-grid button { cursor: pointer; }
.progress-stat-grid strong {
  display: block;
  font-size: 1.2rem;
  line-height: 1.1;
}
.progress-stat-grid span {
  display: block;
  margin-top: 0.25rem;
  color: var(--text-mute);
  font-size: 0.68rem;
  font-weight: 600;
}
.achievement-total {
  color: var(--text-mute);
  font-size: 0.78rem;
  font-weight: 700;
}
.achievement-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.6rem;
}
.achievement-card {
  min-height: 166px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-raised);
  padding: 0.8rem;
}
.achievement-card.locked {
  border-color: var(--border);
  background: var(--bg);
}
.achievement-card.unlocked {
  border-color: var(--accent-border);
  background: linear-gradient(155deg, var(--accent-soft), var(--bg-raised) 68%);
}
.achievement-icon {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  margin-bottom: 0.65rem;
  border-radius: 50%;
  background: var(--bg-soft);
  color: var(--accent);
  font-size: 0.85rem;
  font-weight: 850;
}
.achievement-card.unlocked .achievement-icon {
  background: #0b5c56;
  color: #fff;
}
.achievement-card h3 { margin: 0 0 0.3rem; font-size: 0.82rem; }
.achievement-card p {
  min-height: 2.4em;
  margin: 0 0 0.65rem;
  color: var(--text-mute);
  font-size: 0.68rem;
  line-height: 1.35;
}
.achievement-card > span {
  color: var(--text-mute);
  font-size: 0.65rem;
  font-weight: 750;
}
.achievement-card.unlocked > span { color: var(--accent); }
.local-note {
  margin: 1.25rem 0 0;
  color: var(--text-mute);
  font-size: 0.72rem;
  text-align: center;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: calc(4.5rem + env(safe-area-inset-bottom));
  transform: translateX(-50%);
  z-index: 40;
  padding: 0.45rem 0.85rem;
  border-radius: 999px;
  background: var(--text);
  color: var(--bg);
  font-size: 0.8rem;
  font-weight: 600;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s;
}
.toast.show { opacity: 1; }

/* ---------- Home stats (legacy surfaces still used elsewhere) ---------- */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-bottom: 14px;
}
.stat {
  background: linear-gradient(180deg, var(--bg-raised) 0%, var(--bg-card) 100%);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 14px 8px 12px;
  text-align: center;
  transition: border-color var(--dur-fast) var(--ease-out), transform var(--dur-fast) var(--ease-out);
}
.stat:active { transform: scale(0.98); }
.stat .num {
  font-family: var(--font-display);
  font-size: 1.55rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
}
.stat .lbl {
  font-size: 0.68rem;
  color: var(--text-dim);
  margin-top: 4px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.stat.due .num { color: var(--amber); }
.stat.known .num { color: var(--green); }
.stat.streak .num { color: var(--accent); }

.big-btn {
  display: block;
  width: 100%;
  background: var(--dx-accent);
  color: var(--dx-accent-fg);
  border: none;
  border-radius: var(--radius);
  padding: 16px;
  min-height: 52px;
  font-family: var(--font-ui);
  font-size: 1.05rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  cursor: pointer;
  margin-bottom: 10px;
  box-shadow: 0 6px 20px rgba(62, 207, 191, 0.22);
  transition: transform var(--dur-fast) var(--ease-out), box-shadow var(--dur-fast) var(--ease-out), opacity var(--dur-fast);
}
.big-btn:hover { box-shadow: 0 8px 24px rgba(62, 207, 191, 0.3); }
.big-btn:active { transform: scale(0.985); }
.big-btn.secondary {
  background: var(--bg-raised);
  color: var(--text);
  border: 1px solid var(--border);
  font-weight: 650;
  box-shadow: none;
}
.big-btn.secondary:hover { background: var(--bg-elevated); box-shadow: none; }
.big-btn:disabled {
  opacity: 0.42;
  cursor: default;
  box-shadow: none;
  transform: none;
}

.section-row {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: 0.75rem 0.85rem;
  min-height: 70px;
  margin-bottom: 8px;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  box-shadow: var(--shadow-card);
  transition: border-color var(--dur-fast) var(--ease-out), background var(--dur-fast) var(--ease-out), transform var(--dur-fast) var(--ease-out);
}
button.section-row,
button.concept-row,
button.flashcard {
  width: 100%;
  font: inherit;
  color: inherit;
  text-align: left;
  appearance: none;
  -webkit-appearance: none;
}
.section-row:active {
  transform: scale(0.99);
  border-color: var(--accent-border);
}
.section-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  flex-shrink: 0;
  box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.04);
}
.section-row-main {
  min-width: 0;
  flex: 1;
}
.section-row .name {
  display: block;
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.section-row .counts {
  display: block;
  margin: 0.15rem 0 0.4rem;
  font-size: 0.7rem;
  color: var(--text-mute);
  text-align: left;
  font-weight: 500;
}
.section-chevron {
  flex-shrink: 0;
  color: var(--text-mute);
  font-size: 1.35rem;
}
.progress-track {
  width: 100%;
  height: 7px;
  background: color-mix(in srgb, var(--border) 75%, var(--bg));
  border-radius: var(--radius-pill);
  overflow: hidden;
}
.learning-hero .progress-track { margin: 0; }
.section-row .progress-track { height: 4px; }
/* Motion 2: progress fill */
.progress-fill {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, #2bb8b0, var(--green));
  border-radius: var(--radius-pill);
  transform-origin: left center;
  animation: progress-draw var(--dur-slow) var(--ease-out) both;
  transition: width var(--dur-slow) var(--ease-out);
}
@keyframes progress-draw {
  from { transform: scaleX(0); }
  to { transform: scaleX(1); }
}

h2.head {
  font-family: var(--font-ui);
  font-size: 0.78rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 700;
  margin: 20px 0 10px;
}

/* ---------- Library ---------- */
#search-box {
  width: 100%;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  color: var(--text);
  padding: 14px 14px;
  min-height: 48px;
  font-family: var(--font-ui);
  font-size: 0.95rem;
  margin-bottom: 10px;
  box-shadow: var(--shadow-card);
  transition: border-color var(--dur-fast) var(--ease-out), box-shadow var(--dur-fast) var(--ease-out);
}
#search-box::placeholder { color: var(--text-mute); }
#search-box:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.filter-row { display: flex; gap: 8px; margin-bottom: 12px; flex-wrap: wrap; }
.filter-chip {
  background: var(--bg-raised);
  border: 1px solid var(--border);
  color: var(--text-dim);
  border-radius: var(--radius-pill);
  padding: 0.45rem 0.85rem;
  min-height: 44px;
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 650;
  cursor: pointer;
  box-shadow: var(--shadow-card);
  transition: background var(--dur-fast) var(--ease-out), color var(--dur-fast), border-color var(--dur-fast), transform var(--dur-fast);
}
.filter-chip:active { transform: scale(0.97); }
.filter-chip.active,
html.dark .filter-chip.active {
  background: var(--dx-accent);
  color: var(--dx-accent-fg);
  border-color: var(--dx-accent);
  font-weight: 750;
}

.lib-group {
  margin-bottom: 8px;
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  background: var(--bg-raised);
  box-shadow: var(--shadow-card);
  padding: 2px 10px 6px;
}
.lib-group-head {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  padding: 14px 4px;
  min-height: 48px;
  border: 0;
  background: transparent;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  user-select: none;
}
.lib-group-head .name {
  flex: 1;
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: -0.01em;
}
.lib-group-head .cnt { color: var(--text-dim); font-size: 0.8rem; font-weight: 500; }
.lib-group-head .chev {
  color: var(--text-dim);
  transition: transform var(--dur) var(--ease-out);
}
.lib-group.open .chev { transform: rotate(90deg); }

.concept-row {
  width: 100%;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: 13px 14px;
  margin-bottom: 8px;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  box-shadow: var(--shadow-card);
  transition: border-color var(--dur-fast) var(--ease-out), transform var(--dur-fast) var(--ease-out);
}
.concept-row:active {
  transform: scale(0.99);
  border-color: var(--accent-border);
}
.concept-row .t {
  font-size: 0.93rem;
  font-weight: 650;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  letter-spacing: -0.01em;
}
.row-emoji { font-size: 1.15rem; line-height: 1; flex-shrink: 0; }
.row-author { font-size: 0.72rem; color: var(--text-dim); margin-top: 5px; font-weight: 500; }
.detail-emoji { margin-right: 8px; }
.card-emoji { font-size: 2.6rem; line-height: 1; margin-bottom: 12px; text-align: center; }
.card-emoji.small { font-size: 1.6rem; margin-bottom: 8px; text-align: left; }

mark.hl {
  background: var(--accent-soft);
  color: var(--hl-ink);
  font-weight: 750;
  padding: 0 3px;
  border-radius: 4px;
}

.video-list { display: flex; flex-direction: column; gap: 8px; margin-top: 14px; }
.video-list.compact { margin-top: 12px; }
.video-row {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px;
  min-height: 48px;
  color: var(--text);
}
.video-list.compact .video-row { padding: 8px 10px; }
.video-thumb {
  flex-shrink: 0;
  width: 88px;
  height: 50px;
  object-fit: cover;
  border-radius: 8px;
  background: var(--bg-mid);
}
.video-actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 6px;
  flex-shrink: 0;
}
.video-act {
  font-size: 0.7rem;
  font-weight: 700;
  padding: 7px 11px;
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  border-radius: var(--radius-pill);
  text-decoration: none;
  white-space: nowrap;
  background: rgba(198, 40, 40, 0.1);
  border: 1px solid rgba(198, 40, 40, 0.3);
  color: var(--yt);
  transition: opacity var(--dur-fast);
}
.video-act.primary {
  background: var(--accent-soft);
  border-color: var(--accent-border);
  color: var(--accent);
}
.video-act:active { opacity: 0.8; }

/* One video's concept set (landing target from Wiki Insights) */
.vid-hero {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px;
  margin-bottom: 14px;
}
.vid-hero-thumb {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  border-radius: var(--radius-sm);
  background: var(--bg-mid);
  margin-bottom: 12px;
}
.vid-hero-title { font-size: 1rem; font-weight: 700; line-height: 1.32; }
.vid-hero-meta { font-size: 0.76rem; color: var(--text-dim); margin-top: 4px; }
.vid-hero-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.vid-act {
  flex: 1 1 auto;
  text-align: center;
  font-size: 0.8rem;
  font-weight: 700;
  padding: 10px 14px;
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-pill);
  text-decoration: none;
  background: rgba(198, 40, 40, 0.1);
  border: 1px solid rgba(198, 40, 40, 0.3);
  color: var(--yt);
}
.vid-act.primary {
  background: var(--accent-soft);
  border-color: var(--accent-border);
  color: var(--accent);
}
.vid-act:active { opacity: 0.8; }
.video-yt {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--yt);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  font-weight: 800;
}
.video-meta { display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.video-title { font-size: 0.82rem; font-weight: 650; line-height: 1.3; }
.video-author { font-size: 0.7rem; color: var(--text-dim); }

.badge {
  font-size: 0.62rem;
  font-weight: 800;
  padding: 3px 8px;
  border-radius: var(--radius-pill);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  flex-shrink: 0;
}
.badge.known { background: var(--green-soft); color: var(--green); }
.badge.unknown { background: var(--red-soft); color: var(--red); }
.badge.due { background: var(--amber-soft); color: var(--amber); }

.kw-row { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.kw {
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid var(--accent-border);
  border-radius: var(--radius-pill);
  padding: 4px 10px;
}

/* ---------- Detail ---------- */
.detail-title {
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 750;
  margin-bottom: 10px;
  letter-spacing: -0.02em;
  line-height: 1.25;
}
.detail-def {
  font-size: 0.95rem;
  line-height: 1.6;
  color: var(--text);
  margin: 12px 0;
}
.qa-block { margin: 12px 0; }
.qa-block .q { font-weight: 700; color: var(--accent); margin-bottom: 6px; }
.qa-block .a { color: var(--text-dim); line-height: 1.55; }
.qa-block .a.hidden { display: none; }
.reveal-answer {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  margin-top: 8px;
  padding: 8px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
  background: var(--bg-raised);
  color: var(--accent);
  font: inherit;
  font-size: 0.8rem;
  font-weight: 700;
  cursor: pointer;
}
.qa-block .x {
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px solid var(--border-soft);
  color: var(--text);
  line-height: 1.55;
  font-size: 0.92rem;
}
.related-list { display: flex; flex-direction: column; gap: 8px; }
.related-link {
  background: var(--bg-raised);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 13px 14px;
  min-height: 48px;
  font-family: var(--font-ui);
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  color: var(--text);
  text-align: left;
  transition: border-color var(--dur-fast), background var(--dur-fast);
}
.related-link:active {
  border-color: var(--accent-border);
  background: var(--bg-elevated);
}

.toggle-known-btn {
  width: 100%;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 14px;
  min-height: 48px;
  font-family: var(--font-ui);
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  margin: 14px 0;
  background: var(--bg-raised);
  color: var(--text);
  transition: background var(--dur-fast), border-color var(--dur-fast), color var(--dur-fast);
}
.toggle-known-btn.is-known {
  background: var(--green-soft);
  color: var(--green);
  border-color: rgba(74, 222, 128, 0.45);
}

/* ---------- Study ---------- */
html,
body,
#view-root,
#flashcard {
  overscroll-behavior-x: none;
}

.study-session {
  display: flex;
  flex-direction: column;
  gap: 14px;
  width: 100%;
  max-width: 560px;
  margin-inline: auto;
}

.study-progress-wrap {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.practice-session-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-height: 28px;
}

.study-progress {
  margin: 0;
  font-size: 0.85rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--dx-text);
  text-align: left;
}

.study-progress-bar {
  height: 4px;
  border-radius: 999px;
  background: var(--dx-border);
  overflow: hidden;
}

.study-progress-fill {
  height: 100%;
  width: 0%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--red), var(--accent));
  transition: width 0.28s var(--ease-out);
}

.practice-combo {
  flex: 0 0 auto;
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-pill);
  background: var(--red-soft);
  color: var(--red);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.practice-combo[hidden] { display: none !important; }

.flashcard {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 100%;
  min-height: clamp(220px, 42dvh, 380px);
  padding: clamp(22px, 3vw, 40px);
  border: 1px solid var(--dx-border);
  border-radius: var(--dx-radius);
  background: var(--dx-card);
  color: var(--dx-text);
  font: inherit;
  text-align: center;
  cursor: pointer;
  box-shadow: var(--dx-shadow);
  user-select: none;
  -webkit-user-select: none;
  touch-action: pan-y;
  overscroll-behavior: contain;
  transition:
    border-color 0.28s var(--ease-out),
    box-shadow 0.28s var(--ease-out),
    transform 0.28s var(--ease-out);
}
.flashcard:focus-visible {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}
.flashcard:active { transform: translateY(0) scale(0.995); }
.flashcard.is-flipped {
  border-color: var(--dx-accent);
  justify-content: flex-start;
}
.flashcard-face { width: 100%; }
.flashcard-front {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
  min-height: clamp(180px, 34dvh, 300px);
}
.flashcard-back {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  min-height: clamp(180px, 34dvh, 300px);
  animation: face-settle 0.32s var(--ease-out) both;
}
.flashcard-back[hidden],
.flashcard-front[hidden] { display: none !important; }
.flashcard-hint {
  font-size: 0.82rem;
  color: var(--dx-muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
@keyframes face-settle {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: none; }
}
.flashcard .q-text {
  font-family: var(--font-display);
  font-size: clamp(1.15rem, 4.6vw, 1.65rem);
  font-weight: 700;
  line-height: 1.35;
  letter-spacing: -0.02em;
  max-width: 22em;
}
.flashcard .a-text {
  font-size: 1.15rem;
  font-weight: 650;
  line-height: 1.5;
  max-width: 22em;
}
.flashcard .x-text {
  margin-top: 14px;
  padding: 12px 13px;
  border-radius: var(--radius-sm);
  background: var(--accent-soft);
  border: 1px solid var(--accent-border);
  font-size: 0.9rem;
  line-height: 1.5;
  color: var(--text);
}
.flashcard .x-label {
  display: block;
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 4px;
}
.flashcard .concept-name {
  margin-top: 16px;
  font-size: 0.85rem;
  color: var(--accent);
  font-weight: 700;
}
.flashcard .tap-hint {
  margin-top: auto;
  padding-top: 18px;
  text-align: center;
  color: var(--text-mute);
  font-size: 0.78rem;
  font-weight: 500;
}

.hint-btn {
  align-self: flex-start;
  background: none;
  border: 1px dashed var(--border);
  color: var(--text-dim);
  border-radius: var(--radius-pill);
  padding: 10px 14px;
  min-height: 44px;
  font-family: var(--font-ui);
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  margin-top: 14px;
  transition: border-color var(--dur-fast), color var(--dur-fast);
}
.hint-btn:active {
  border-color: var(--accent);
  color: var(--accent);
}

#btn-reveal {
  width: 100%;
  min-height: 48px;
  border-radius: var(--dx-radius);
  border: 1px solid var(--dx-border);
  background: var(--dx-card);
  color: var(--dx-text);
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}
#btn-reveal[hidden] { display: none !important; }

.study-actions {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 6px;
  position: sticky;
  bottom: 0;
  z-index: 4;
  margin-top: auto;
  padding: 8px 0 calc(8px + env(safe-area-inset-bottom));
  background: var(--dx-bg);
  border-top: 1px solid var(--dx-border);
}
.study-actions[hidden] { display: none !important; }
.btn-rate {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  min-width: 0;
  min-height: 52px;
  padding: 6px 2px;
  border: 1px solid var(--dx-border);
  border-radius: var(--radius-sm);
  background: var(--dx-card);
  color: var(--dx-text);
  font: inherit;
  font-size: 0.72rem;
  font-weight: 800;
  line-height: 1.1;
  cursor: pointer;
  overflow: hidden;
}
.btn-rate:active { transform: translateY(1px) scale(0.97); }
.rate-key {
  font-size: 0.6rem;
  font-weight: 700;
  opacity: 0.45;
  letter-spacing: 0.02em;
  white-space: nowrap;
}
.btn-again { border-color: color-mix(in srgb, var(--red) 45%, transparent); color: var(--red); }
.btn-again:active { background: var(--red-soft); }
.btn-hard { border-color: color-mix(in srgb, var(--amber) 55%, transparent); color: var(--amber); }
.btn-hard:active { background: var(--amber-soft); }
.btn-good { border-color: color-mix(in srgb, var(--accent) 45%, transparent); color: var(--accent); }
.btn-good:active { background: var(--accent-soft); }
.btn-easy {
  border-color: color-mix(in srgb, var(--accent) 75%, transparent);
  background: var(--accent-soft);
  color: var(--accent);
}
.btn-easy:active { filter: brightness(0.97); }
.btn-known { color: var(--dx-text); }

.known-row { display: flex; gap: 8px; margin-top: 10px; }
.known-btn {
  flex: 1;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  color: var(--text-dim);
  border-radius: var(--radius-sm);
  padding: 13px 4px;
  min-height: 48px;
  font-family: var(--font-ui);
  font-size: 0.8rem;
  font-weight: 700;
  cursor: pointer;
  transition: color var(--dur-fast), border-color var(--dur-fast), background var(--dur-fast);
}
.known-btn.mark-known.active,
.known-btn.mark-known:active {
  color: var(--green);
  border-color: rgba(74, 222, 128, 0.5);
  background: var(--green-soft);
}
.flashcard .q-text.q-compact {
  font-size: 0.95rem;
  line-height: 1.4;
  margin-bottom: 4px;
  color: var(--dx-muted);
}
.card-fold {
  width: 100%;
  margin-top: 8px;
  text-align: left;
}
.card-fold-btn {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  width: 100%;
  min-height: 44px;
  padding: 8px 2px;
  border: 0;
  border-top: 1px solid var(--dx-border);
  background: transparent;
  color: var(--dx-text);
  font: 700 0.82rem/1.2 var(--dx-font);
  text-align: left;
  cursor: pointer;
}
.card-fold-chev {
  color: var(--dx-muted);
  font-size: 1.1rem;
  transition: transform var(--dur-fast) var(--ease-out);
}
.card-fold-btn[aria-expanded="true"] .card-fold-chev { transform: rotate(90deg); }
.card-fold-panel { padding: 0 0 8px; }
.card-fold-panel[hidden] { display: none; }
.card-fold-panel .video-list,
.card-fold-panel .x-text { margin-top: 0; }
.card-fold-panel .kw-row { margin-top: 0; }

.concept-open {
  display: block;
  width: 100%;
  margin: 0;
  padding: 0;
  border: 0;
  background: transparent;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
}
.concept-row.is-known-row { cursor: default; }
.unhide-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  min-height: 44px;
  margin-top: 10px;
  padding: 0 12px;
  border-radius: var(--dx-radius-sm);
  border: 1px solid var(--dx-border);
  background: var(--dx-card-solid);
  color: var(--dx-text);
  font: 700 0.85rem/1 var(--dx-font);
  cursor: pointer;
}
.unhide-btn:active { transform: scale(0.98); }

.ux-continue {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  width: 100%;
  min-height: 44px;
  margin: 0 0 10px;
  padding: 10px 16px;
  border: 1px solid var(--dx-border);
  border-radius: var(--dx-radius);
  background: var(--dx-card);
  box-shadow: var(--dx-shadow);
  color: var(--dx-text);
  font: inherit;
  font-weight: 650;
  text-align: left;
  cursor: pointer;
}
.ux-continue[hidden] { display: none !important; }
.ux-continue > span:first-child { min-width: 0; flex: 1; }
.ux-continue small {
  display: block;
  margin-bottom: 2px;
  overflow: hidden;
  color: var(--dx-muted);
  font-size: 0.72rem;
  font-weight: 650;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.ux-continue strong { display: block; font-size: 1rem; font-weight: 650; }
.ux-continue-go {
  flex: 0 0 auto;
  min-width: 44px;
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--dx-accent);
  font-size: 1.25rem;
}
.ux-keys {
  margin: 0;
  text-align: center;
  color: var(--dx-muted);
  font-size: 0.75rem;
  line-height: 1.4;
}

#flashcard.ux-dragging { transition: none; z-index: 2; }
#flashcard.ux-left { border-color: var(--red); }
#flashcard.ux-right { border-color: var(--accent); }
#flashcard.ux-up { border-color: var(--dx-accent); }
.ux-swipe-label {
  position: absolute;
  top: 12px;
  left: 50%;
  z-index: 3;
  display: none;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  padding: 0 14px;
  border: 1px solid var(--dx-border);
  border-radius: 999px;
  background: var(--dx-card-solid);
  color: var(--dx-text);
  font-size: 0.8125rem;
  font-weight: 700;
  pointer-events: none;
  transform: translateX(-50%);
}
.ux-swipe-label.is-on { display: flex; }
.ux-swipe-label.is-again { color: var(--red); border-color: var(--red); }
.ux-swipe-label.is-good { color: var(--accent); border-color: var(--accent); }
.ux-swipe-label.is-move,
.ux-swipe-label.is-reveal { color: var(--dx-accent); border-color: var(--dx-accent); }

.practice-focus-exit { display: none; }
.practice-focus-exit[hidden] { display: none !important; }

html.practice-focus,
html.practice-focus body {
  background-color: var(--dx-bg);
  overflow: hidden;
  overflow-anchor: none;
}
html.practice-focus #app {
  height: 100dvh;
  max-height: 100dvh;
  max-width: 100%;
}
html.practice-focus #topbar,
html.practice-focus .suite-nav,
html.practice-focus .dx-tabs,
html.practice-focus #tabbar,
html.practice-focus #connect,
html.practice-focus .ux-keys {
  display: none !important;
}
html.practice-focus #view-root {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  padding:
    env(safe-area-inset-top, 0px)
    max(12px, env(safe-area-inset-right, 0px))
    0
    max(12px, env(safe-area-inset-left, 0px));
}
html.practice-focus .study-session {
  flex: 1 1 auto;
  gap: 8px;
  width: 100%;
  max-width: 720px;
  min-height: 0;
  margin-inline: auto;
  padding-bottom: calc(96px + env(safe-area-inset-bottom, 0px));
  overflow: hidden;
}
html.practice-focus .study-progress-wrap {
  flex: 0 0 auto;
  margin-inline: -12px;
  padding: 0 12px 6px;
  border: 0;
  border-radius: 0;
  background: var(--dx-bg);
  box-shadow: none;
}
html.practice-focus .practice-session-row {
  min-height: 44px;
  padding-right: 48px;
}
html.practice-focus .flashcard {
  flex: 1 1 auto;
  min-height: 0;
  overflow: auto;
  justify-content: flex-start;
}
html.practice-focus .flashcard-front,
html.practice-focus .flashcard-back { min-height: 0; justify-content: center; }
html.practice-focus .flashcard:not(.is-flipped) .flashcard-front { min-height: 100%; }
html.practice-focus .practice-focus-exit {
  position: fixed;
  z-index: 60;
  top: env(safe-area-inset-top, 0px);
  right: env(safe-area-inset-right, 0px);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  min-width: 44px;
  min-height: 44px;
  margin: 0;
  padding: 0;
  border: 1px solid var(--dx-border);
  border-radius: 999px;
  background: var(--dx-card-solid);
  color: var(--dx-text);
  cursor: pointer;
  touch-action: manipulation;
}
html.practice-focus .practice-focus-exit:active { transform: scale(0.96); }
html.practice-focus .study-actions {
  position: fixed;
  z-index: 40;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
  padding:
    8px
    max(12px, env(safe-area-inset-right, 0px))
    calc(8px + env(safe-area-inset-bottom, 0px))
    max(12px, env(safe-area-inset-left, 0px));
  background: var(--dx-bg);
  border-top: 1px solid var(--dx-border);
}
html.practice-focus #btn-reveal:not([hidden]) {
  position: fixed;
  z-index: 40;
  left: 0;
  right: 0;
  bottom: calc(8px + env(safe-area-inset-bottom, 0px));
  display: block;
  width: min(720px, calc(100% - max(12px, env(safe-area-inset-left, 0px)) - max(12px, env(safe-area-inset-right, 0px))));
  margin-inline: auto;
}
@media (max-width: 400px) {
  html.practice-focus .flashcard { padding: 16px 12px; }
  html.practice-focus .btn-rate { min-height: 48px; padding: 6px 1px; font-size: 0.68rem; }
}

.undo-toast {
  position: fixed;
  z-index: 80;
  left: 50%;
  bottom: calc(5rem + env(safe-area-inset-bottom));
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 12px;
  max-width: calc(100vw - 24px);
  min-height: 44px;
  padding: 6px 6px 6px 14px;
  border-radius: 999px;
  background: var(--dx-text);
  color: var(--dx-bg);
  box-shadow: var(--dx-shadow);
  font-size: 0.85rem;
  font-weight: 700;
}
html.practice-focus .undo-toast {
  bottom: calc(78px + env(safe-area-inset-bottom));
}
.undo-toast span { white-space: nowrap; }
.undo-toast button {
  min-height: 36px;
  min-width: 44px;
  border: 0;
  border-radius: 999px;
  background: var(--dx-bg);
  color: var(--dx-text);
  font: inherit;
  font-weight: 800;
  padding: 0 12px;
  cursor: pointer;
}

.done-panel { text-align: center; padding: 44px 16px; }
.done-panel .emoji { font-size: 3rem; }
.done-panel h3 {
  font-family: var(--font-display);
  margin: 12px 0 6px;
  font-weight: 750;
  letter-spacing: -0.02em;
}
.done-panel p { color: var(--text-dim); font-size: 0.9rem; margin-bottom: 20px; }
.done-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin: 16px 0 20px;
  text-align: center;
}
.done-stats strong { display: block; font-size: 1.15rem; }
.done-stats span {
  display: block;
  margin-top: 0.2rem;
  color: var(--text-mute);
  font-size: 0.68rem;
  font-weight: 600;
}
.recap-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  margin: 16px 0 12px;
  text-align: center;
}
.recap-stats strong {
  display: block;
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: -0.03em;
}
.recap-stats span {
  display: block;
  margin-top: 0.2rem;
  color: var(--text-mute);
  font-size: 0.68rem;
  font-weight: 600;
}
.recap-coach {
  color: var(--text-mute);
  font-size: 0.85rem;
  line-height: 1.45;
  margin-bottom: 16px;
}

.empty-note {
  color: var(--text-dim);
  text-align: center;
  padding: 36px 12px;
  font-size: 0.9rem;
  line-height: 1.5;
}

/* =========================================================
   Analytics view (markup supplied by Frontend / analytics.js)
   ========================================================= */

.analytics-hero {
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(500px 220px at 0% 0%, rgba(62, 207, 191, 0.16), transparent 60%),
    linear-gradient(160deg, var(--bg-raised) 0%, var(--bg-card) 100%);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 20px 18px 18px;
  margin-bottom: 14px;
  box-shadow: var(--shadow-card);
}
.analytics-hero h2 {
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 750;
  letter-spacing: -0.02em;
  margin-bottom: 6px;
}
.analytics-hero p {
  color: var(--text-dim);
  font-size: 0.88rem;
  line-height: 1.45;
  font-weight: 500;
}
.analytics-hero .hero-meta {
  margin-top: 12px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.analytics-hero .hero-chip {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid var(--accent-border);
  border-radius: var(--radius-pill);
  padding: 6px 10px;
}

.analytics-kpis {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  margin-bottom: 14px;
}
.kpi {
  background: linear-gradient(180deg, var(--bg-raised) 0%, var(--bg-card) 100%);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 14px 12px;
  min-height: 88px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
}
.kpi .kpi-label {
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-dim);
}
.kpi .kpi-value {
  font-family: var(--font-display);
  font-size: 1.55rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
}
.kpi .kpi-sub {
  font-size: 0.72rem;
  color: var(--text-mute);
  font-weight: 500;
}
.kpi.accent .kpi-value { color: var(--accent); }
.kpi.good .kpi-value { color: var(--green); }
.kpi.warn .kpi-value { color: var(--amber); }

/* 30-day chart */
.progress-chart,
.sparkline {
  background: linear-gradient(180deg, var(--bg-raised) 0%, var(--bg-card) 100%);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 16px 14px 14px;
  margin-bottom: 14px;
  box-shadow: var(--shadow-card);
}
.progress-chart .chart-head,
.sparkline .chart-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 12px;
}
.progress-chart .chart-title,
.sparkline .chart-title {
  font-size: 0.78rem;
  font-weight: 750;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-dim);
}
.progress-chart .chart-value,
.sparkline .chart-value {
  font-family: var(--font-display);
  font-weight: 750;
  font-size: 1.1rem;
  color: var(--text);
}
.sparkline-track,
.progress-chart-track {
  display: flex;
  align-items: flex-end;
  gap: 3px;
  height: 72px;
  width: 100%;
}
.sparkline-bar,
.progress-chart-bar {
  flex: 1;
  min-width: 0;
  border-radius: 3px 3px 1px 1px;
  background: linear-gradient(180deg, var(--accent) 0%, rgba(62, 207, 191, 0.35) 100%);
  transform-origin: bottom center;
  animation: bar-rise var(--dur-slow) var(--ease-out) both;
  opacity: 0.85;
}
.sparkline-bar.is-today,
.progress-chart-bar.is-today {
  background: linear-gradient(180deg, #7af0e2 0%, var(--accent) 100%);
  opacity: 1;
  box-shadow: 0 0 10px rgba(62, 207, 191, 0.35);
}
.sparkline-bar.is-empty,
.progress-chart-bar.is-empty {
  background: rgba(255, 255, 255, 0.06);
  min-height: 3px !important;
  opacity: 1;
}
@keyframes bar-rise {
  from { transform: scaleY(0); opacity: 0.2; }
  to { transform: scaleY(1); opacity: 0.85; }
}

/* Timeline — Motion 4: draw-in */
.timeline {
  background: linear-gradient(180deg, var(--bg-raised) 0%, var(--bg-card) 100%);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 16px 14px;
  margin-bottom: 14px;
  box-shadow: var(--shadow-card);
}
.timeline .timeline-head {
  font-size: 0.78rem;
  font-weight: 750;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-dim);
  margin-bottom: 14px;
}
.timeline-day {
  display: grid;
  grid-template-columns: 52px 1fr 36px;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
  opacity: 0;
  transform: translateX(-8px);
  animation: timeline-in var(--dur-slow) var(--ease-out) forwards;
}
.timeline-day.timeline-day-wide {
  grid-template-columns: minmax(52px, 28%) 1fr 40px;
  grid-template-rows: auto auto;
}
.timeline-day.timeline-day-wide .day-label {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.timeline-day .timeline-counts {
  grid-column: 1 / -1;
  font-size: 0.72rem;
  color: var(--text-mute);
  font-weight: 500;
  margin-top: -4px;
  padding-left: 0;
}
.timeline-day:nth-child(1) { animation-delay: 40ms; }
.timeline-day:nth-child(2) { animation-delay: 80ms; }
.timeline-day:nth-child(3) { animation-delay: 120ms; }
.timeline-day:nth-child(4) { animation-delay: 160ms; }
.timeline-day:nth-child(5) { animation-delay: 200ms; }
.timeline-day:nth-child(6) { animation-delay: 240ms; }
.timeline-day:nth-child(7) { animation-delay: 280ms; }
.timeline-day:nth-child(n+8) { animation-delay: 320ms; }
@keyframes timeline-in {
  to {
    opacity: 1;
    transform: translateX(0);
  }
}
.timeline-day .day-label {
  font-size: 0.72rem;
  font-weight: 650;
  color: var(--text-dim);
  font-variant-numeric: tabular-nums;
}
.timeline-bar {
  height: 8px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-pill);
  overflow: hidden;
  position: relative;
}
.timeline-bar > span,
.timeline-bar .fill {
  display: block;
  height: 100%;
  border-radius: var(--radius-pill);
  background: linear-gradient(90deg, #2bb8b0, var(--accent));
  transform-origin: left center;
  animation: progress-draw calc(var(--dur-slow) + 80ms) var(--ease-out) both;
}
.timeline-day .day-count {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--text);
  text-align: right;
  font-variant-numeric: tabular-nums;
}
.timeline-empty {
  text-align: center;
  padding: 28px 12px;
  color: var(--text-dim);
  font-size: 0.88rem;
  line-height: 1.5;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.02);
  margin-bottom: 14px;
}

/* Optional activity heatmap strip */
.heatmap {
  display: flex;
  gap: 3px;
  flex-wrap: nowrap;
  overflow-x: auto;
  padding: 12px 0 0;
  margin: 10px 0 0;
  border-top: 1px solid var(--border-soft);
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.progress-chart .heatmap { margin-bottom: 0; }
.heatmap::-webkit-scrollbar { display: none; }
.heatmap-cell {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
  border-radius: 3px;
  background: rgba(255, 255, 255, 0.06);
  transition: transform var(--dur-fast) var(--ease-out);
}
.heatmap-cell:active { transform: scale(1.2); }
.heatmap-cell.l1 { background: rgba(62, 207, 191, 0.28); }
.heatmap-cell.l2 { background: rgba(62, 207, 191, 0.5); }
.heatmap-cell.l3 { background: rgba(62, 207, 191, 0.72); }
.heatmap-cell.l4 { background: var(--accent); box-shadow: 0 0 8px rgba(62, 207, 191, 0.35); }

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .tab::before,
  .nav-tab::before { transition: none; }
  .progress-fill,
  .timeline-bar > span,
  .timeline-bar .fill,
  .sparkline-bar,
  .progress-chart-bar,
  .flashcard,
  .timeline-day {
    animation: none !important;
    opacity: 1;
    transform: none;
  }
  #flashcard.ux-dragging { transform: none !important; }
}

/* Focus visibility for keyboard users */
.tab:focus-visible,
.nav-tab:focus-visible,
.skip-link:focus-visible,
.primary-action:focus-visible,
.status-stats button:focus-visible,
.icon-btn:focus-visible,
.big-btn:focus-visible,
.btn-rate:focus-visible,
.known-btn:focus-visible,
.practice-focus-exit:focus-visible,
#btn-reveal:focus-visible,
.ux-continue:focus-visible,
.card-fold-btn:focus-visible,
.unhide-btn:focus-visible,
.concept-open:focus-visible,
.undo-toast button:focus-visible,
.filter-chip:focus-visible,
.section-row:focus-visible,
button.section-row:focus-visible,
.concept-row:focus-visible,
button.concept-row:focus-visible,
#card:focus-visible,
.flashcard:focus-visible,
button.flashcard:focus-visible,
.related-link:focus-visible,
.toggle-known-btn:focus-visible,
.lib-group-head:focus-visible,
.hint-btn:focus-visible,
#btn-connect:focus-visible,
.video-act:focus-visible,
.vid-act:focus-visible,
.milestone-card > button:focus-visible,
.achievement-card:focus-visible,
.reveal-answer:focus-visible,
#search-box:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

@media (min-width: 720px) {
  #view-root {
    padding: 1.25rem 1.5rem calc(6.25rem + env(safe-area-inset-bottom));
  }
  .learning-hero,
  .level-card {
    padding: 1.25rem;
  }
  .recap-stats { grid-template-columns: repeat(3, 1fr); }
  .achievement-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (max-width: 520px) {
  #view-root {
    padding-inline: 0.75rem;
  }
  .level-card { align-items: flex-start; }
  .level-orb { width: 50px; height: 50px; }
  .level-card > strong { display: none; }
}

html.dark #tabbar {
  box-shadow: 0 -8px 24px rgba(0, 0, 0, 0.28);
}

/* AWS study */
.aws-study {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  min-width: 0;
  max-width: 100%;
}
.aws-study h2 {
  margin: 0.1rem 0 0.55rem;
  font-size: 1.2rem;
  line-height: 1.2;
}
.aws-study h3 {
  margin: 0;
  font-size: 0.98rem;
  line-height: 1.3;
  overflow-wrap: anywhere;
}
.aws-card {
  min-width: 0;
  max-width: 100%;
  background: var(--dx-card);
  border: 1px solid var(--dx-border);
  border-radius: var(--dx-radius);
  padding: 0.9rem;
  box-shadow: var(--dx-shadow);
  color: var(--dx-text);
}
.aws-banner,
.aws-form-error {
  margin: 0;
  padding: 0.65rem 0.75rem;
  border-radius: 12px;
  background: color-mix(in srgb, var(--amber) 18%, var(--dx-card-solid));
  color: var(--amber);
  font-size: 0.92rem;
  font-weight: 750;
}
.aws-banner-warn,
.aws-form-error {
  background: color-mix(in srgb, var(--red) 14%, var(--dx-card-solid));
  color: var(--red);
}
.aws-status {
  margin: 0;
  min-height: 1.1rem;
  color: var(--text-dim);
  font-size: 0.78rem;
  font-weight: 650;
}
.aws-status:empty { display: none; }
.aws-when,
.aws-latest,
.aws-notes,
.aws-reviewed,
.aws-empty {
  margin: 0.35rem 0 0;
  color: var(--text-dim);
  font-size: 0.92rem;
  line-height: 1.4;
  overflow-wrap: anywhere;
}
.aws-latest.aws-pass,
.aws-pass { color: var(--green); }
.aws-miss { color: var(--text); }
.aws-badge {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  margin-top: 0.45rem;
  padding: 0.15rem 0.6rem;
  border-radius: var(--radius-pill);
  background: var(--bg-elevated);
  color: var(--text-dim);
  font-size: 0.75rem;
  font-weight: 750;
}
.aws-badge.on {
  background: var(--green-soft);
  color: var(--green);
}
.aws-readiness { margin-top: 0.8rem; }
.aws-meter-row,
.aws-domain-head,
.aws-topic-main,
.aws-score,
.aws-link-row,
.aws-actions,
.aws-weak li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
}
.aws-meter-row { margin-bottom: 0.35rem; font-weight: 700; }
.aws-meter {
  height: 10px;
  overflow: hidden;
  border-radius: var(--radius-pill);
  background: var(--bg-elevated);
}
.aws-meter > span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: var(--accent);
}
.aws-domain + .aws-domain { border-top: 1px solid var(--border); }
.aws-domain-head {
  width: 100%;
  min-height: 44px;
  flex-wrap: wrap;
  padding: 0.45rem 0;
  border: 0;
  background: transparent;
  color: var(--text);
  font: inherit;
  font-weight: 750;
  text-align: left;
  cursor: pointer;
}
.aws-domain-meta {
  color: var(--text-mute);
  font-size: 0.75rem;
  font-weight: 650;
}
.aws-domain-body { padding: 0 0 0.7rem; }
.aws-topic {
  min-width: 0;
  padding: 0.55rem 0 0.7rem;
}
.aws-topic + .aws-topic { border-top: 1px solid var(--border-soft); }
.aws-topic-main h3 { flex: 1 1 auto; min-width: 0; }
.aws-seg {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin-top: 0.45rem;
}
.aws-seg-btn,
.aws-btn,
.aws-details summary {
  min-height: 44px;
  min-width: 44px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--bg-card);
  color: var(--text);
  font: inherit;
  font-weight: 750;
  cursor: pointer;
}
.aws-seg-btn {
  padding: 0 0.7rem;
}
.aws-seg-btn[aria-pressed="true"],
html.dark .aws-seg-btn[aria-pressed="true"] {
  background: var(--dx-accent);
  border-color: var(--dx-accent);
  color: var(--dx-accent-fg);
}
.aws-btn {
  padding: 0.4rem 0.75rem;
}
.aws-btn.primary,
html.dark .aws-btn.primary {
  background: var(--dx-accent);
  border-color: var(--dx-accent);
  color: var(--dx-accent-fg);
}
.aws-btn.danger {
  background: var(--red-soft);
  border-color: transparent;
  color: var(--red);
}
.aws-notes { white-space: pre-wrap; }
.aws-links,
.aws-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.45rem;
}
.aws-link,
.aws-link-text {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  color: var(--accent);
  font-weight: 700;
  overflow-wrap: anywhere;
}
.aws-link-row {
  width: 100%;
  margin-bottom: 0.35rem;
}
.aws-form { margin-top: 0.7rem; }
.aws-field {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  margin-bottom: 0.55rem;
}
.aws-field span,
.aws-check {
  color: var(--text-dim);
  font-size: 0.75rem;
  font-weight: 750;
}
.aws-field input,
.aws-field textarea,
.aws-pair input {
  width: 100%;
  min-height: 44px;
  padding: 0.45rem 0.65rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--bg);
  color: var(--text);
  font: inherit;
  font-size: 16px;
}
.aws-check {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  min-height: 44px;
  margin: 0.2rem 0 0.6rem;
  font-size: 0.95rem;
}
.aws-check input { width: 44px; height: 44px; margin: 0; }
.aws-details { margin: 0.3rem 0 0.7rem; }
.aws-details summary {
  display: flex;
  align-items: center;
  padding: 0 0.7rem;
  list-style: none;
}
.aws-details summary::-webkit-details-marker { display: none; }
.aws-pair {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 0.6fr) minmax(0, 0.6fr);
  gap: 0.35rem;
  align-items: center;
  margin-top: 0.45rem;
}
.aws-pair span {
  color: var(--text-dim);
  font-size: 0.78rem;
  font-weight: 700;
  overflow-wrap: anywhere;
}
.aws-chart {
  display: block;
  width: 100%;
  height: auto;
  margin: 0.2rem 0 0.4rem;
}
.aws-chart-ref {
  stroke: var(--amber);
  stroke-width: 1.5;
  stroke-dasharray: 4 3;
}
.aws-chart-line {
  fill: none;
  stroke: var(--accent);
  stroke-width: 2.5;
  stroke-linejoin: round;
  stroke-linecap: round;
}
.aws-chart-dot { fill: var(--accent); }
.aws-chart-label {
  fill: var(--text-mute);
  font-size: 10px;
  font-weight: 700;
}
.aws-scores,
.aws-weak {
  margin: 0.2rem 0 0.7rem;
  padding: 0;
  list-style: none;
}
.aws-score {
  display: grid;
  grid-template-columns: 6.5rem minmax(0, 1fr) auto auto;
  column-gap: 0.4rem;
  align-items: center;
  min-height: 44px;
  padding: 0.35rem 0;
  border-top: 1px solid var(--border-soft);
}
.aws-weak li {
  flex-wrap: wrap;
  justify-content: flex-start;
  min-height: 44px;
  padding: 0.35rem 0;
  border-top: 1px solid var(--border-soft);
}
.aws-source { min-width: 0; overflow-wrap: anywhere; }
.aws-by-domain {
  grid-column: 1 / -1;
  color: var(--text-mute);
  font-size: 0.75rem;
}
.aws-weak li { align-items: flex-start; flex-direction: column; gap: 0.1rem; }
.aws-btn:focus-visible,
.aws-seg-btn:focus-visible,
.aws-domain-head:focus-visible,
.aws-link:focus-visible,
.aws-field input:focus-visible,
.aws-field textarea:focus-visible {
  outline: 2px solid var(--dx-accent);
  outline-offset: 2px;
}

/* Text that sits on the art, outside a card. */
#loading,
.empty-note,
.timeline-empty,
.local-note,
.home-section > .section-heading,
.home-section > .section-heading h2,
.home-section > .section-heading .eyebrow,
.home-section > .section-heading .text-action,
.home-section > .section-heading .achievement-total {
  color: var(--dx-on-bg);
  text-shadow: 0 1px 2px hsl(0 0% 0% / 0.85), 0 0 12px hsl(0 0% 0% / 0.6);
}

.dx-actions { min-width: 0; }
#topbar-status { max-width: min(42vw, 46%); }