/* ===================================================================
   EPI FLASHCARDS — style.css
   Design: Academic / Medical — deep navy + teal accent, clean serif
   =================================================================== */

/* --- Fonts --- */
@import url('https://api.fontshare.com/v2/css?f[]=satoshi@400,500,600,700&display=swap');
@import url('https://fonts.googleapis.com/css2?family=DM+Serif+Display:ital@0;1&display=swap');

/* --- Design Tokens --- */
:root {
  /* Type scale */
  --text-xs:   clamp(0.75rem,  0.7rem  + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem  + 0.35vw, 1rem);
  --text-base: clamp(1rem,     0.95rem + 0.25vw, 1.125rem);
  --text-lg:   clamp(1.125rem, 1rem    + 0.75vw, 1.5rem);
  --text-xl:   clamp(1.5rem,   1.2rem  + 1.25vw, 2.25rem);
  --text-2xl:  clamp(2rem,     1.2rem  + 2.5vw,  3.5rem);

  /* Spacing */
  --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;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;

  /* Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1.25rem;
  --radius-full: 9999px;

  /* Transitions */
  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);
  --transition-flip: 600ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(10, 20, 50, 0.08);
  --shadow-md: 0 4px 16px rgba(10, 20, 50, 0.10);
  --shadow-lg: 0 12px 40px rgba(10, 20, 50, 0.14);
  --shadow-card: 0 8px 32px rgba(10, 20, 50, 0.12), 0 2px 8px rgba(10, 20, 50, 0.08);

  /* Fonts */
  --font-display: 'DM Serif Display', 'Georgia', serif;
  --font-body: 'Satoshi', 'Inter', sans-serif;

  /* Content widths */
  --content-default: 860px;
}

/* --- Light Mode (default) --- */
:root, [data-theme="light"] {
  --color-bg:              #f0f2f7;
  --color-surface:         #ffffff;
  --color-surface-2:       #f8f9fc;
  --color-surface-offset:  #eef0f5;
  --color-divider:         #dde0ea;
  --color-border:          #cdd1df;

  --color-text:            #111827;
  --color-text-muted:      #6b7280;
  --color-text-faint:      #9ca3af;
  --color-text-inverse:    #f9fafb;

  /* Deep navy as primary for academic feel */
  --color-primary:         #1e3a5f;
  --color-primary-hover:   #162d4a;
  --color-primary-active:  #0f1f35;
  --color-primary-highlight: #dce6f0;

  /* Teal accent */
  --color-accent:          #0a7b8e;
  --color-accent-hover:    #086475;
  --color-accent-active:   #064d5b;
  --color-accent-highlight: #d0eaed;

  /* Utility */
  --color-success:         #1a7a45;
  --color-success-highlight: #d1ece0;
  --color-warning:         #b45309;
  --color-warning-highlight: #fef3c7;
  --color-error:           #b91c1c;
  --color-error-highlight: #fee2e2;
  --color-bookmark:        #d97706;
  --color-bookmark-active: #f59e0b;

  /* Card faces */
  --card-front-bg:         #1e3a5f;
  --card-front-text:       #f0f6ff;
  --card-front-accent:     #7db8d4;
  --card-back-bg:          #ffffff;
  --card-back-text:        #111827;
  --card-back-ref:         #6b7280;
}

/* --- Dark Mode --- */
[data-theme="dark"], @media (prefers-color-scheme: dark) { :root:not([data-theme]) {
  --color-bg:              #0d1117;
  --color-surface:         #161b22;
  --color-surface-2:       #1c2128;
  --color-surface-offset:  #13181f;
  --color-divider:         #21262d;
  --color-border:          #30363d;

  --color-text:            #e6edf3;
  --color-text-muted:      #8b949e;
  --color-text-faint:      #484f58;
  --color-text-inverse:    #0d1117;

  --color-primary:         #58a6ff;
  --color-primary-hover:   #388bfd;
  --color-primary-active:  #1f6feb;
  --color-primary-highlight: #1f3a5c;

  --color-accent:          #39d0e0;
  --color-accent-hover:    #1ab8c9;
  --color-accent-active:   #0fa0b0;
  --color-accent-highlight: #1a3a3e;

  --color-success:         #3fb950;
  --color-success-highlight: #1a3a25;
  --color-warning:         #d29922;
  --color-warning-highlight: #3a2c10;
  --color-error:           #f85149;
  --color-error-highlight: #3a1515;
  --color-bookmark:        #f0a533;
  --color-bookmark-active: #fbbf24;

  --color-divider:         #21262d;
  --color-border:          #30363d;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.5);
  --shadow-card: 0 8px 32px rgba(0,0,0,0.4), 0 2px 8px rgba(0,0,0,0.3);

  --card-front-bg:         #1c2e4a;
  --card-front-text:       #e8f0fe;
  --card-front-accent:     #58a6ff;
  --card-back-bg:          #161b22;
  --card-back-text:        #e6edf3;
  --card-back-ref:         #8b949e;
}}

[data-theme="dark"] {
  --color-bg:              #0d1117;
  --color-surface:         #161b22;
  --color-surface-2:       #1c2128;
  --color-surface-offset:  #13181f;
  --color-divider:         #21262d;
  --color-border:          #30363d;

  --color-text:            #e6edf3;
  --color-text-muted:      #8b949e;
  --color-text-faint:      #484f58;
  --color-text-inverse:    #0d1117;

  --color-primary:         #58a6ff;
  --color-primary-hover:   #388bfd;
  --color-primary-active:  #1f6feb;
  --color-primary-highlight: #1f3a5c;

  --color-accent:          #39d0e0;
  --color-accent-hover:    #1ab8c9;
  --color-accent-active:   #0fa0b0;
  --color-accent-highlight: #1a3a3e;

  --color-success:         #3fb950;
  --color-success-highlight: #1a3a25;
  --color-warning:         #d29922;
  --color-warning-highlight: #3a2c10;
  --color-error:           #f85149;
  --color-error-highlight: #3a1515;
  --color-bookmark:        #f0a533;
  --color-bookmark-active: #fbbf24;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.5);
  --shadow-card: 0 8px 32px rgba(0,0,0,0.4), 0 2px 8px rgba(0,0,0,0.3);

  --card-front-bg:         #1c2e4a;
  --card-front-text:       #e8f0fe;
  --card-front-accent:     #58a6ff;
  --card-back-bg:          #161b22;
  --card-back-text:        #e6edf3;
  --card-back-ref:         #8b949e;
}

/* --- Base Reset --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  -webkit-text-size-adjust: none;
  text-size-adjust: none;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}

body {
  min-height: 100dvh;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
  display: flex;
  flex-direction: column;
}

img, picture, video, canvas, svg { display: block; max-width: 100%; height: auto; }
button { cursor: pointer; background: none; border: none; font: inherit; color: inherit; }
a, button, [role="button"] {
  transition: color var(--transition-interactive),
              background var(--transition-interactive),
              border-color var(--transition-interactive),
              box-shadow var(--transition-interactive),
              opacity var(--transition-interactive);
}
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* ===================================================================
   LAYOUT
   =================================================================== */

.app-wrapper {
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
}

/* --- Header --- */
.app-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-divider);
  padding: var(--space-4) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.header-brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.header-logo {
  width: 40px;
  height: 40px;
  flex-shrink: 0;
}

.header-title-group {
  display: flex;
  flex-direction: column;
}

.header-title {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 400;
  line-height: 1.1;
  color: var(--color-text);
  letter-spacing: -0.01em;
}

.header-subtitle {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  font-weight: 500;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.btn-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  background: transparent;
}
.btn-icon:hover {
  color: var(--color-text);
  background: var(--color-surface-offset);
}

/* --- Main content area --- */
.app-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: var(--space-8) var(--space-4);
  gap: var(--space-6);
  max-width: var(--content-default);
  width: 100%;
  margin: 0 auto;
}

/* ===================================================================
   CONTROLS PANEL (top settings bar)
   =================================================================== */

.controls-panel {
  width: 100%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-4) var(--space-6);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  box-shadow: var(--shadow-sm);
}

.controls-left {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  flex-wrap: wrap;
}

.controls-right {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex-wrap: wrap;
}

/* Toggle group: Manual / Timer */
.mode-toggle-group {
  display: flex;
  align-items: center;
  background: var(--color-surface-offset);
  border-radius: var(--radius-full);
  padding: var(--space-1);
  gap: 2px;
}

.mode-toggle-btn {
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  background: transparent;
  white-space: nowrap;
}
.mode-toggle-btn.active {
  background: var(--color-primary);
  color: white;
  box-shadow: var(--shadow-sm);
}
.mode-toggle-btn:hover:not(.active) {
  color: var(--color-text);
  background: var(--color-divider);
}

/* Timer duration selector */
.timer-options {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.timer-label {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  font-weight: 500;
  white-space: nowrap;
}

.timer-select {
  appearance: none;
  -webkit-appearance: none;
  background: var(--color-surface-offset);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-2) var(--space-6) var(--space-2) var(--space-3);
  font-size: var(--text-sm);
  font-family: var(--font-body);
  color: var(--color-text);
  cursor: pointer;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%236b7280' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
}
.timer-select:focus { outline: 2px solid var(--color-accent); }

/* Shuffle toggle */
.shuffle-toggle {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  cursor: pointer;
  user-select: none;
}
.shuffle-toggle input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--color-accent);
  cursor: pointer;
}
.shuffle-toggle:hover { color: var(--color-text); }

/* Counter badge */
.counter-badge {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  background: var(--color-primary-highlight);
  color: var(--color-primary);
  border-radius: var(--radius-full);
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: 700;
}
[data-theme="dark"] .counter-badge {
  background: var(--color-primary-highlight);
  color: var(--color-primary);
}
.counter-number {
  font-size: var(--text-base);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

/* Progress bar */
.progress-bar-wrap {
  width: 100%;
  height: 4px;
  background: var(--color-divider);
  border-radius: var(--radius-full);
  overflow: hidden;
}
.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  border-radius: var(--radius-full);
  transition: width 400ms ease;
  width: 0%;
}

/* ===================================================================
   FLASHCARD SCENE
   =================================================================== */

.card-scene {
  width: 100%;
  perspective: 1200px;
  perspective-origin: 50% 40%;
}

.card-stage {
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
  position: relative;
  /* Height: responsive aspect ratio ~3:2 */
  aspect-ratio: 3 / 2;
  min-height: 280px;
  max-height: 420px;
}

.flashcard {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform var(--transition-flip);
  cursor: pointer;
  border-radius: var(--radius-xl);
}

.flashcard.is-flipped {
  transform: rotateY(180deg);
}

/* Card faces */
.card-face {
  position: absolute;
  inset: 0;
  border-radius: var(--radius-xl);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow: var(--shadow-card);
}

/* Front face */
.card-front {
  background: var(--card-front-bg);
  color: var(--card-front-text);
  padding: var(--space-8) var(--space-10);
  justify-content: center;
  align-items: center;
  text-align: center;
  gap: var(--space-4);
}

.card-front::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--color-accent), #7db8d4);
  border-radius: var(--radius-xl) var(--radius-xl) 0 0;
}

.card-label {
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  opacity: 0.6;
}

.card-question {
  font-family: var(--font-display);
  font-size: clamp(1.2rem, 1rem + 1.5vw, 1.8rem);
  line-height: 1.25;
  font-weight: 400;
  color: var(--card-front-text);
  max-width: 52ch;
}

.card-hint {
  font-size: var(--text-xs);
  opacity: 0.5;
  margin-top: var(--space-2);
}

/* Back face */
.card-back {
  background: var(--card-back-bg);
  color: var(--card-back-text);
  transform: rotateY(180deg);
  border: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
}

.card-back-inner {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: var(--space-6) var(--space-10);
  gap: var(--space-3);
  overflow-y: auto;
}

.card-answer {
  font-size: clamp(0.95rem, 0.85rem + 0.5vw, 1.1rem);
  line-height: 1.65;
  color: var(--card-back-text);
  max-width: 58ch;
}

.card-reference {
  font-size: var(--text-xs);
  color: var(--card-back-ref);
  font-style: italic;
  margin-top: var(--space-2);
}

/* Card back footer (action buttons) */
.card-back-footer {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-6);
  border-top: 1px solid var(--color-divider);
  background: var(--color-surface-2);
  flex-shrink: 0;
}

/* Timer ring overlay */
.timer-ring-wrap {
  position: absolute;
  top: var(--space-4);
  right: var(--space-4);
  z-index: 10;
  opacity: 0;
  transition: opacity 300ms;
}
.timer-ring-wrap.visible { opacity: 1; }

.timer-ring-svg { transform: rotate(-90deg); }

.timer-ring-bg {
  fill: none;
  stroke: rgba(255,255,255,0.15);
  stroke-width: 3;
}
.timer-ring-fill {
  fill: none;
  stroke: var(--card-front-accent);
  stroke-width: 3;
  stroke-linecap: round;
  transition: stroke-dashoffset 1s linear;
}

.timer-ring-text {
  font-size: var(--text-sm);
  font-weight: 700;
  fill: var(--card-front-accent);
  text-anchor: middle;
  dominant-baseline: central;
  font-family: var(--font-body);
  font-variant-numeric: tabular-nums;
}

/* ===================================================================
   NAVIGATION BUTTONS
   =================================================================== */

.nav-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-4);
  width: 100%;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
  border: none;
  cursor: pointer;
}

.btn-primary {
  background: var(--color-primary);
  color: white;
  box-shadow: var(--shadow-sm);
}
.btn-primary:hover {
  background: var(--color-primary-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}
.btn-primary:active {
  background: var(--color-primary-active);
  transform: translateY(0);
  box-shadow: var(--shadow-sm);
}

.btn-secondary {
  background: var(--color-surface);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}
.btn-secondary:hover {
  background: var(--color-surface-offset);
  border-color: var(--color-text-muted);
}

.btn-accent {
  background: var(--color-accent);
  color: white;
  box-shadow: var(--shadow-sm);
}
.btn-accent:hover {
  background: var(--color-accent-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.btn-flip {
  background: var(--color-primary);
  color: white;
  padding: var(--space-3) var(--space-8);
  border-radius: var(--radius-full);
  font-weight: 700;
  box-shadow: var(--shadow-md);
  font-size: var(--text-base);
}
.btn-flip:hover {
  background: var(--color-primary-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* Learn more button (on card back) */
.btn-learn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--text-xs);
  font-weight: 600;
  background: var(--color-accent-highlight);
  color: var(--color-accent);
  border: 1px solid color-mix(in srgb, var(--color-accent) 30%, transparent);
  text-decoration: none;
}
.btn-learn:hover {
  background: var(--color-accent);
  color: white;
}

/* Bookmark button (on card back) */
.btn-bookmark {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--text-xs);
  font-weight: 600;
  background: var(--color-surface-offset);
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
}
.btn-bookmark:hover {
  background: var(--color-warning-highlight);
  color: var(--color-bookmark);
  border-color: color-mix(in srgb, var(--color-bookmark) 30%, transparent);
}
.btn-bookmark.is-bookmarked {
  background: var(--color-warning-highlight);
  color: var(--color-bookmark-active);
  border-color: color-mix(in srgb, var(--color-bookmark-active) 40%, transparent);
}
.btn-bookmark.is-bookmarked svg { fill: var(--color-bookmark-active); }

/* ===================================================================
   EMPTY / START STATE
   =================================================================== */

.empty-state {
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
  aspect-ratio: 3 / 2;
  min-height: 280px;
  max-height: 420px;
  background: var(--color-surface);
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-xl);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-4);
  text-align: center;
  padding: var(--space-8);
}
.empty-state-icon {
  color: var(--color-text-faint);
}
.empty-state-title {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  color: var(--color-text);
}
.empty-state-desc {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  max-width: 36ch;
}

/* ===================================================================
   BOOKMARKED TERMS SECTION
   =================================================================== */

.bookmarks-section {
  width: 100%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.bookmarks-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--space-6);
  border-bottom: 1px solid var(--color-divider);
  background: var(--color-surface-2);
  cursor: pointer;
  user-select: none;
}

.bookmarks-header-left {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.bookmarks-title {
  font-weight: 700;
  font-size: var(--text-base);
  color: var(--color-text);
}

.bookmark-count-badge {
  background: var(--color-warning-highlight);
  color: var(--color-bookmark);
  font-size: var(--text-xs);
  font-weight: 700;
  padding: 2px var(--space-2);
  border-radius: var(--radius-full);
}

.bookmarks-toggle-icon {
  color: var(--color-text-muted);
  transition: transform var(--transition-interactive);
}
.bookmarks-section.is-open .bookmarks-toggle-icon {
  transform: rotate(180deg);
}

.bookmarks-body {
  display: none;
  padding: var(--space-4) var(--space-6);
  flex-direction: column;
  gap: var(--space-3);
}
.bookmarks-section.is-open .bookmarks-body {
  display: flex;
}

.bookmarks-textarea {
  width: 100%;
  min-height: 140px;
  padding: var(--space-3) var(--space-4);
  background: var(--color-surface-offset);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  color: var(--color-text);
  resize: vertical;
  line-height: 1.7;
}
.bookmarks-textarea:focus {
  outline: 2px solid var(--color-accent);
  border-color: var(--color-accent);
}

.bookmarks-actions {
  display: flex;
  gap: var(--space-3);
  align-items: center;
  flex-wrap: wrap;
}

.bookmarks-empty-msg {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  text-align: center;
  padding: var(--space-6) 0;
}

.copy-feedback {
  font-size: var(--text-xs);
  color: var(--color-success);
  font-weight: 600;
  opacity: 0;
  transition: opacity 300ms;
}
.copy-feedback.visible { opacity: 1; }

/* ===================================================================
   FOOTER
   =================================================================== */

.app-footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-divider);
  padding: var(--space-4) var(--space-6);
  text-align: center;
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-4);
  flex-wrap: wrap;
}
.app-footer a {
  color: var(--color-text-muted);
  text-decoration: none;
  font-weight: 500;
}
.app-footer a:hover { color: var(--color-primary); }

/* ===================================================================
   TOAST NOTIFICATIONS
   =================================================================== */

.toast-area {
  position: fixed;
  bottom: var(--space-6);
  left: 50%;
  transform: translateX(-50%);
  z-index: 999;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-2);
  pointer-events: none;
}

.toast {
  background: var(--color-text);
  color: var(--color-bg);
  padding: var(--space-3) var(--space-5);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  box-shadow: var(--shadow-lg);
  animation: toastIn 250ms cubic-bezier(0.16, 1, 0.3, 1) forwards,
             toastOut 250ms 1.8s ease forwards;
  white-space: nowrap;
}

@keyframes toastIn {
  from { opacity: 0; transform: translateY(8px) scale(0.95); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}
@keyframes toastOut {
  from { opacity: 1; transform: translateY(0); }
  to   { opacity: 0; transform: translateY(-4px); }
}

/* ===================================================================
   RESPONSIVE
   =================================================================== */

@media (max-width: 600px) {
  .app-header { padding: var(--space-3) var(--space-4); }
  .header-subtitle { display: none; }
  .app-main { padding: var(--space-5) var(--space-3); gap: var(--space-4); }
  .controls-panel { padding: var(--space-3) var(--space-4); }
  .controls-left, .controls-right { gap: var(--space-3); }
  .card-front, .card-back-inner { padding: var(--space-5) var(--space-6); }
  .card-question { font-size: clamp(1rem, 0.9rem + 1vw, 1.4rem); }
  .card-back-footer { flex-wrap: wrap; }
  .nav-row { gap: var(--space-3); }
  .btn { padding: var(--space-3) var(--space-4); }
  .bookmarks-section .bookmarks-body { padding: var(--space-3) var(--space-4); }
}

/* ===================================================================
   ANIMATIONS & MICRO-INTERACTIONS
   =================================================================== */

@keyframes cardIn {
  from { opacity: 0; transform: translateY(12px) scale(0.98); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}
.card-scene {
  animation: cardIn 350ms cubic-bezier(0.16, 1, 0.3, 1);
}

/* Shine sweep on card front */
.card-front::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg,
    rgba(255,255,255,0) 40%,
    rgba(255,255,255,0.04) 50%,
    rgba(255,255,255,0) 60%
  );
  border-radius: inherit;
  pointer-events: none;
}

/* Pulse on timer about to expire */
@keyframes timerPulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}
.timer-ring-fill.urgent {
  stroke: #f59e0b;
  animation: timerPulse 800ms ease infinite;
}

/* ===================================================================
   ADDITIONS: Category picker, cookie banner, references, license
   =================================================================== */

/* -------- CATEGORY PICKER -------- */
.category-picker {
  background: var(--color-surface);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-xl);
  padding: var(--space-6) var(--space-5);
  margin: var(--space-4) 0 var(--space-6) 0;
  box-shadow: var(--shadow-sm);
}

.category-picker-intro {
  text-align: center;
  margin-bottom: var(--space-5);
}

.category-picker-title {
  font-family: 'DM Serif Display', Georgia, serif;
  font-size: var(--text-xl);
  color: var(--color-text);
  margin: 0 0 var(--space-2) 0;
  letter-spacing: -0.01em;
}

.category-picker-desc {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  max-width: 56ch;
  margin: 0 auto;
  line-height: 1.55;
}

.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-4);
}

.category-card {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: var(--space-2);
  padding: var(--space-5) var(--space-4);
  background: var(--color-surface-2);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  cursor: pointer;
  text-align: left;
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease, background 0.18s ease;
  font-family: inherit;
  color: inherit;
  position: relative;
  overflow: hidden;
}

.category-card:hover,
.category-card:focus-visible {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
  background: var(--color-surface);
  outline: none;
}

.category-card:focus-visible {
  box-shadow: 0 0 0 3px rgba(30, 58, 95, 0.25), var(--shadow-md);
}

.category-icon {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  background: var(--color-primary-highlight);
  color: var(--color-primary);
  margin-bottom: var(--space-1);
}

.category-public  .category-icon { background: var(--color-success-highlight); color: var(--color-success); }
.category-student .category-icon { background: var(--color-accent-highlight);  color: var(--color-accent); }
.category-advanced .category-icon { background: var(--color-primary-highlight); color: var(--color-primary); }
.category-all     .category-icon { background: var(--color-warning-highlight); color: var(--color-warning); }

.category-title {
  font-family: 'Satoshi', system-ui, sans-serif;
  font-weight: 700;
  font-size: var(--text-base);
  color: var(--color-text);
  line-height: 1.25;
}

.category-desc {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  line-height: 1.5;
  flex: 1;
}

.category-count {
  margin-top: var(--space-2);
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-text-faint);
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

/* -------- SELECTED CATEGORY BAR -------- */
.selected-category-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  flex-wrap: wrap;
  margin: var(--space-2) 0 var(--space-4) 0;
}

.selected-category-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-full);
  background: var(--color-primary-highlight);
  color: var(--color-primary);
  font-size: var(--text-xs);
  font-weight: 600;
  border: 1px solid var(--color-primary);
}

.selected-category-badge .badge-dot {
  opacity: 0.55;
}

.selected-category-badge .badge-count {
  font-weight: 500;
  opacity: 0.85;
}

.btn-link {
  background: none;
  border: none;
  color: var(--color-accent);
  font-family: inherit;
  font-size: var(--text-xs);
  font-weight: 600;
  cursor: pointer;
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius-sm);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.btn-link:hover {
  color: var(--color-accent-hover);
  background: var(--color-accent-highlight);
  text-decoration: none;
}

/* -------- COOKIE BANNER -------- */
.cookie-banner {
  position: fixed;
  left: var(--space-4);
  right: var(--space-4);
  bottom: var(--space-4);
  z-index: 200;
  background: var(--color-surface);
  border: 1.5px solid var(--color-primary);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: var(--space-4) var(--space-5);
  display: none;
  max-width: 920px;
  margin: 0 auto;
}

.cookie-banner.is-visible {
  display: block;
  animation: cookieSlideUp 0.32s ease;
}

@keyframes cookieSlideUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

.cookie-banner-inner {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: var(--space-4);
  align-items: center;
}

.cookie-banner-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-full);
  background: var(--color-primary-highlight);
  color: var(--color-primary);
  flex-shrink: 0;
}

.cookie-banner-text {
  min-width: 0;
}

.cookie-banner-title {
  font-family: 'Satoshi', system-ui, sans-serif;
  font-weight: 700;
  font-size: var(--text-sm);
  color: var(--color-text);
  margin: 0 0 var(--space-1) 0;
}

.cookie-banner-desc {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.55;
}

.cookie-banner-actions {
  display: flex;
  gap: var(--space-2);
  flex-shrink: 0;
}

@media (max-width: 700px) {
  .cookie-banner-inner {
    grid-template-columns: 1fr;
    text-align: center;
  }
  .cookie-banner-icon {
    margin: 0 auto;
  }
  .cookie-banner-actions {
    justify-content: center;
  }
}

/* -------- REFERENCES -------- */
.references-section {
  margin: var(--space-8) 0 var(--space-4) 0;
  padding: var(--space-6) var(--space-5);
  background: var(--color-surface-2);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-lg);
}

.references-title {
  font-family: 'DM Serif Display', Georgia, serif;
  font-size: var(--text-lg);
  color: var(--color-text);
  margin: 0 0 var(--space-2) 0;
}

.references-intro {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin: 0 0 var(--space-4) 0;
  line-height: 1.55;
}

.references-list {
  margin: 0 0 var(--space-4) 0;
  padding-left: var(--space-5);
  font-size: var(--text-sm);
  color: var(--color-text);
  line-height: 1.65;
}

.references-list li {
  margin-bottom: var(--space-3);
  padding-left: var(--space-1);
}

.references-list a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.references-list a:hover {
  color: var(--color-accent-hover);
}

.references-note {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  font-style: italic;
  margin: var(--space-3) 0 0 0;
  line-height: 1.55;
}

/* -------- CC LICENSE -------- */
.license-section {
  margin: var(--space-6) 0 var(--space-4) 0;
  padding: var(--space-5);
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
}

.license-inner {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.license-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  color: var(--color-text);
  text-decoration: none;
  padding: var(--space-2);
  border-radius: var(--radius-md);
  background: var(--color-surface-offset);
  transition: background 0.18s ease;
  flex-shrink: 0;
}

.license-badge:hover {
  background: var(--color-primary-highlight);
  color: var(--color-primary);
}

.license-text {
  flex: 1;
  min-width: 240px;
}

.license-line {
  margin: 0 0 var(--space-2) 0;
  font-size: var(--text-sm);
  color: var(--color-text);
  line-height: 1.55;
}

.license-line a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.license-line-small {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  margin-bottom: 0;
}

/* -------- DARK THEME OVERRIDES for new components -------- */
[data-theme="dark"] .category-card {
  background: var(--color-surface-2);
  border-color: var(--color-border);
}
[data-theme="dark"] .category-card:hover,
[data-theme="dark"] .category-card:focus-visible {
  background: var(--color-surface);
}
[data-theme="dark"] .cookie-banner {
  border-color: var(--color-accent);
}
[data-theme="dark"] .license-section,
[data-theme="dark"] .references-section {
  background: var(--color-surface-2);
}