/*
 * StudyApp Flashcards visual adapter.
 * Neutral/amber roles mirror StudyApp Workspace BETA light and dark modes.
 * Typography, spacing, shape and accessibility follow ecosystem-framework v1.2.
 */
:root {
  color-scheme: light;
  --color-background: #f7f7f5;
  --color-surface: #ffffff;
  --color-surface-subtle: #f4f4f1;
  --color-text: #1f1f1d;
  --color-text-muted: #5b5b55;
  --color-border: #d7d7d2;
  --color-border-strong: #bdbdb7;
  --app-accent: #97671f;
  --app-accent-strong: #765019;
  --app-on-accent: #ffffff;
  --color-focus: #92400e;
  --color-primary-background: #eee9f2;
  --color-primary-text: #59466d;
  --color-primary-border: #cfc3d9;
  --color-repeat-background: #f3eee2;
  --color-repeat-text: #6b572f;
  --color-positive-background: #e6eee9;
  --color-positive-text: #365947;
  --color-progress-track: #e7e5e0;
  --color-progress-fill: #906f4c;
  --color-error: #a3312a;
  --font-sans: Inter, "Noto Sans", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-size-sm: 0.875rem;
  --font-size-md: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --radius-sm: 0.375rem;
  --radius-md: 0.625rem;
  --radius-lg: 0.875rem;
  --radius-xl: 1.25rem;
  --radius-pill: 9999px;
  --touch-target-min: 2.75rem;
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-background);
  font-synthesis: none;
}

:root[data-appearance="dark"] {
  color-scheme: dark;
  --color-background: #171716;
  --color-surface: #20201f;
  --color-surface-subtle: #252523;
  --color-text: #f2f2ef;
  --color-text-muted: #c5c5bf;
  --color-border: #3a3a36;
  --color-border-strong: #585851;
  --app-accent: #e7b477;
  --app-accent-strong: #d39a58;
  --app-on-accent: #181817;
  --color-focus: #e1ad6f;
  --color-primary-background: #59446c;
  --color-primary-text: #ffffff;
  --color-primary-border: #745b89;
  --color-repeat-background: #53462c;
  --color-repeat-text: #f5e3b7;
  --color-positive-background: #365548;
  --color-positive-text: #eef7ef;
  --color-progress-track: #3c3c37;
  --color-progress-fill: #e7b477;
  --color-error: #ffb2a9;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; min-height: 100vh; background: var(--color-background); }
button, select { font: inherit; }
button { cursor: pointer; }
button, select, a { -webkit-tap-highlight-color: transparent; }
button:focus-visible, select:focus-visible, a:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 3px;
}

.header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
}
.header-inner {
  max-width: 72rem;
  margin: auto;
  min-height: 4.5rem;
  padding: var(--space-3) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}
.brand, .header-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-3);
}
.brand-home {
  display: inline-flex;
  align-items: center;
  min-height: var(--touch-target-min);
  color: var(--color-text);
  font-size: var(--font-size-lg);
  font-weight: 700;
  letter-spacing: -0.02em;
  text-decoration: none;
}
.brand-home:hover { text-decoration: underline; text-underline-offset: 0.2em; }
.brand-section { color: var(--color-text-muted); font-size: var(--font-size-sm); font-weight: 700; }
.version {
  font-size: 0.75rem;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-1) var(--space-2);
}
.header-actions {
  justify-content: flex-end;
  gap: var(--space-4);
}
.header-actions a, .theme-toggle {
  color: var(--color-text-muted);
  font-size: 0.8125rem;
  font-weight: 700;
}
.header-actions a {
  display: inline-flex;
  align-items: center;
  min-height: var(--touch-target-min);
  text-decoration: none;
  padding: var(--space-3) 0;
}
.header-actions a:hover { text-decoration: underline; text-underline-offset: 0.2em; }
.header-actions .ecosystem-return { color: var(--app-accent-strong); }
.studyapp-return {
  color: var(--color-text) !important;
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  background: var(--color-surface-subtle);
  padding: var(--space-3) !important;
}
.studyapp-return:hover { background: var(--color-progress-track); }
.theme-toggle {
  min-width: var(--touch-target-min);
  min-height: var(--touch-target-min);
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: transparent;
}
.theme-toggle:hover { background: var(--color-surface-subtle); color: var(--color-text); }

.shell {
  max-width: 72rem;
  margin: auto;
  padding: var(--space-6) var(--space-6) var(--space-8);
}
.intro {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: var(--space-6);
  padding: var(--space-2) 0 var(--space-6);
}
.eyebrow, .card-kicker {
  color: var(--app-accent-strong);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  margin: 0;
}
.intro h1 {
  font-size: clamp(1.5rem, 2.4vw, 2rem);
  line-height: 1.2;
  letter-spacing: -0.025em;
  margin: var(--space-2) 0;
}
.intro h1 em { font-style: normal; color: var(--app-accent-strong); }
.intro p:not(.eyebrow) {
  max-width: 38rem;
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  line-height: 1.55;
  margin: 0;
}
.deck-control {
  width: 17rem;
  flex: none;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
}
.deck-control label {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 700;
  margin-bottom: var(--space-2);
}
.deck-control select {
  min-height: var(--touch-target-min);
  width: 100%;
  background: var(--color-surface);
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-md);
  padding: var(--space-2);
  color: var(--color-text);
}
.muted { font-size: 0.8125rem !important; margin: var(--space-2) 0 0 !important; color: var(--color-text-muted) !important; }

.session {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
}
.session-top {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: var(--space-4);
}
.count { font-size: var(--font-size-lg); font-weight: 700; margin: var(--space-2) 0 0; }
.pill {
  font-size: 0.8125rem;
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-surface-subtle);
  color: var(--color-text-muted);
}
.meter {
  height: 0.5rem;
  border-radius: var(--radius-pill);
  background: var(--color-progress-track);
  overflow: hidden;
  margin: var(--space-5) 0;
}
.meter > div {
  width: 0%;
  height: 100%;
  background: var(--color-progress-fill);
  transition: width 200ms ease;
}
.flashcard {
  min-height: 15.5rem;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
  padding: var(--space-8) var(--space-6);
  background: var(--color-surface-subtle);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}
.flashcard h3 {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin: var(--space-4) 0;
}
.dot {
  display: inline-block;
  vertical-align: middle;
  width: 0.5rem;
  height: 0.5rem;
  margin-right: var(--space-2);
  background: var(--app-accent);
  border-radius: 50%;
}
.card-helper { color: var(--color-text-muted); font-size: var(--font-size-sm); }
#answer-side { text-align: left; max-width: 42rem; width: 100%; margin: auto; }
#answer-side h3 { font-size: var(--font-size-2xl); margin: var(--space-3) 0 var(--space-5); }
.answer-block { padding: var(--space-4) 0 var(--space-1); border-top: 1px solid var(--color-border); }
.answer-block > span { color: var(--app-accent-strong); font-size: 0.75rem; font-weight: 700; }
.answer-block p { line-height: 1.55; margin: var(--space-2) 0; font-size: var(--font-size-md); }
.complete-icon {
  width: 3rem;
  height: 3rem;
  display: grid;
  place-items: center;
  margin: auto;
  background: var(--color-positive-background);
  color: var(--color-positive-text);
  border-radius: 50%;
  font-size: var(--font-size-2xl);
}
#done-side p { color: var(--color-text-muted); line-height: 1.55; }

.action-bar {
  display: flex;
  justify-content: center;
  gap: var(--space-3);
  flex-wrap: wrap;
  margin-top: var(--space-5);
}
.btn {
  min-height: var(--touch-target-min);
  padding: var(--space-3) var(--space-4);
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-md);
  background: var(--color-surface-subtle);
  color: var(--color-text);
  font-weight: 700;
  transition: background 150ms ease, border-color 150ms ease;
}
.btn:hover { background: var(--color-progress-track); }
.btn.primary {
  background: var(--color-primary-background);
  border-color: var(--color-primary-border);
  color: var(--color-primary-text);
}
.btn.primary:hover { filter: brightness(0.95); }
:root[data-appearance="dark"] .btn.primary:hover { filter: brightness(1.15); }
.btn.repeat {
  background: var(--color-repeat-background);
  border-color: var(--color-border);
  color: var(--color-repeat-text);
}
.btn.success {
  background: var(--color-positive-background);
  border-color: var(--color-border);
  color: var(--color-positive-text);
}
.btn.repeat:hover, .btn.success:hover { filter: brightness(0.96); }
:root[data-appearance="dark"] .btn.repeat:hover,
:root[data-appearance="dark"] .btn.success:hover { filter: brightness(1.14); }
#grade-actions { display: flex; gap: var(--space-3); }
kbd {
  display: inline-block;
  font-family: inherit;
  font-size: 0.75rem;
  padding: 0.1rem var(--space-1);
  margin-left: var(--space-2);
  border: 1px solid currentColor;
  border-radius: var(--radius-sm);
}
.session-hint {
  color: var(--color-text-muted);
  text-align: center;
  font-size: 0.8125rem;
  margin: var(--space-4) 0 0;
}

.footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  margin-top: var(--space-5);
  padding: var(--space-5) 0;
  border-bottom: 1px solid var(--color-border);
}
.footer strong { font-size: var(--font-size-sm); }
.footer p { color: var(--color-text-muted); font-size: 0.8125rem; margin: var(--space-1) 0; }
.footer-actions { display: flex; flex-wrap: wrap; gap: var(--space-2); }
.footer-actions .btn { font-size: 0.8125rem; }
.notice { min-height: 1.5rem; font-size: var(--font-size-sm); color: var(--color-positive-text); }
.notice.error { color: var(--color-error); }
.legal {
  color: var(--color-text-muted);
  font-size: 0.75rem;
  text-align: center;
  line-height: 1.6;
  margin-top: var(--space-4);
}
[hidden] { display: none !important; }

@media (max-width: 800px) {
  .header-inner { flex-wrap: wrap; align-items: start; }
  .header-actions { justify-content: flex-start; }
  .intro { flex-direction: column; align-items: stretch; }
  .deck-control { width: 100%; }
}
@media (max-width: 600px) {
  .header-inner, .shell { padding-left: var(--space-4); padding-right: var(--space-4); }
  .header-actions { gap: var(--space-2); }
  .header-actions .ecosystem-return { width: 100%; }
  .session { padding: var(--space-4); }
  .flashcard { padding: var(--space-6) var(--space-4); min-height: 14rem; }
  .footer { align-items: stretch; flex-direction: column; }
  .footer-actions .btn { flex: 1 1 8rem; }
  .action-bar, .action-bar > .btn { width: 100%; }
  #grade-actions { flex-direction: column; width: 100%; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .meter > div, .btn { transition: none; }
}

/* Quick / Deep study mode selector */
.mode-panel {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-4);
  margin: 0 0 var(--space-5);
  padding: var(--space-4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
}
.mode-panel p { margin: var(--space-1) 0; color: var(--color-text-muted); font-size: var(--font-size-sm); }
.mode-switch { display: flex; gap: var(--space-2); }
.mode-switch button {
  min-height: var(--touch-target-min);
  padding: var(--space-2) var(--space-6);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border-strong);
  background: var(--color-surface-subtle);
  color: var(--color-text);
  font: inherit;
  font-weight: 700;
}
.mode-switch button[aria-pressed="true"] {
  border-color: var(--app-accent-strong);
  background: var(--color-repeat-background);
  color: var(--color-repeat-text);
}
.mode-switch button:focus-visible { outline: 3px solid var(--color-focus); outline-offset: 2px; }