/* ---------------------------------------------------------------- tokens
   FlashcardQuiz design system — sage/teal palette.
   Shared by landing + app. Single source of truth. */

:root {
  /* Light mode */
  --bg: #BEE9DA;
  --bg-alt: #A8D9C4;
  --surface: #F4FBF7;
  --surface-2: #BBCAAA;
  --surface-elevated: #FFFFFF;
  --accent: #7CD5C8;
  --accent-deep: #23766B;
  --accent-soft: rgba(124, 213, 200, 0.22);
  --accent-hover: #5FC4B5;
  --on-accent: #1A2E28;
  --on-secondary: #FFFFFF;
  --secondary: #4E5D3C;
  --secondary-soft: rgba(155, 174, 139, 0.2);
  --text: #312116;
  --text-secondary: #4A3C32;
  --text-muted: #5C514B;
  --border: rgba(49, 33, 22, 0.12);
  --border-strong: rgba(49, 33, 22, 0.22);
  --green: #2A734F;
  --green-soft: rgba(61, 154, 110, 0.15);
  --rose: #A84646;
  --rose-soft: rgba(196, 91, 91, 0.14);
  --amber: #7E5C23;
  --amber-soft: rgba(184, 134, 59, 0.15);
  --grad: linear-gradient(135deg, #7CD5C8 0%, #9BAE8B 100%);
  --grad-hero: linear-gradient(135deg, #7CD5C8 0%, #A8D9C4 50%, #9BAE8B 100%);
  --shadow-sm: 0 1px 3px rgba(49, 33, 22, 0.07);
  --shadow: 0 4px 14px rgba(49, 33, 22, 0.09);
  --shadow-lg: 0 14px 36px rgba(49, 33, 22, 0.12);
  --shadow-glow: 0 0 0 3px rgba(124, 213, 200, 0.3);
  --radius: 12px;
  --radius-lg: 18px;
  --radius-xl: 24px;
  --font: "DM Sans", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", "Cascadia Mono", monospace;
  --sidebar-w: 240px;
  --sidenav-w: 72px;
  --topnav-h: 60px;
  --transition-fast: 0.15s ease;
  --transition-med: 0.25s ease;
}

:root[data-theme="dark"] {
  --bg: #121816;
  --bg-alt: #0D1210;
  --surface: #1B2421;
  --surface-2: #222D29;
  --surface-elevated: #212C28;
  --accent: #66C2B4;
  --accent-deep: #4DA99B;
  --accent-soft: rgba(102, 194, 180, 0.10);
  --accent-hover: #7DD1C4;
  --on-accent: #121816;
  --on-secondary: #121816;
  --secondary: #9BAE8B;
  --secondary-soft: rgba(155, 174, 139, 0.16);
  --text: #E3ECE8;
  --text-secondary: #B8C4BE;
  --text-muted: #A1AFA9;
  --border: #2A3833;
  --border-strong: #3A4A44;
  --green: #5CBF8E;
  --green-soft: rgba(92, 191, 142, 0.14);
  --rose: #D47A7A;
  --rose-soft: rgba(212, 122, 122, 0.10);
  --amber: #D4A85C;
  --amber-soft: rgba(212, 168, 92, 0.14);
  --grad: linear-gradient(135deg, #66C2B4 0%, #9BAE8B 100%);
  --grad-hero: linear-gradient(135deg, #66C2B4 0%, #2A3833 50%, #9BAE8B 100%);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow: 0 4px 14px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 14px 36px rgba(0, 0, 0, 0.45);
  --shadow-glow: 0 0 0 3px rgba(102, 194, 180, 0.28);
}

/* ---------------------------------------------------------------- derived accent
   Selecting any palette re-tints the soft wash, hover, glow, and gradients
   automatically (applyPrefs only sets --accent). The static declarations
   above stay as the fallback for browsers without color-mix. */
@supports (background: color-mix(in srgb, red 50%, blue)) {
  :root {
    --accent-soft: color-mix(in srgb, var(--accent) 22%, transparent);
    --accent-hover: color-mix(in srgb, var(--accent) 78%, black);
    --shadow-glow: 0 0 0 3px color-mix(in srgb, var(--accent) 30%, transparent);
    --grad: linear-gradient(135deg, var(--accent) 0%, var(--secondary) 100%);
    --grad-hero: linear-gradient(135deg, var(--accent) 0%, var(--bg-alt) 50%, var(--secondary) 100%);
  }
  :root[data-theme="dark"] {
    --accent-soft: color-mix(in srgb, var(--accent) 10%, transparent);
    --accent-hover: color-mix(in srgb, var(--accent) 78%, white);
    --shadow-glow: 0 0 0 3px color-mix(in srgb, var(--accent) 28%, transparent);
    --grad: linear-gradient(135deg, var(--accent) 0%, var(--secondary) 100%);
    --grad-hero: linear-gradient(135deg, var(--accent) 0%, var(--bg-alt) 50%, var(--secondary) 100%);
  }
}

html.fs-compact { zoom: 0.92; }
html.fs-large { zoom: 1.12; }

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--text);
  font-family: var(--font);
  line-height: 1.6;
  background: var(--bg);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

::selection { background: var(--accent-soft); }

::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 999px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

/* ---------------------------------------------------------------- animations */

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: none; }
}
@keyframes slideInRight {
  from { opacity: 0; transform: translateX(12px); }
  to { opacity: 1; transform: none; }
}
@keyframes scaleIn {
  from { opacity: 0; transform: scale(0.95); }
  to { opacity: 1; transform: none; }
}
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}
@keyframes shimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-4px); }
  40% { transform: translateX(4px); }
  60% { transform: translateX(-3px); }
  80% { transform: translateX(3px); }
}
@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}
@keyframes floatSlow {
  0%, 100% { transform: translateY(0) rotate(var(--r, 0deg)); }
  50% { transform: translateY(-12px) rotate(var(--r, 0deg)); }
}
@keyframes spin { to { transform: rotate(360deg); } }
@keyframes progressSlide {
  0% { margin-left: -30%; }
  100% { margin-left: 100%; }
}

.animate-in { animation: fadeIn 0.3s ease both; }

/* ---------------------------------------------------------------- reduced motion */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ---------------------------------------------------------------- skeleton */

.skeleton {
  background: linear-gradient(90deg, var(--surface-2) 25%, var(--border) 50%, var(--surface-2) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s ease-in-out infinite;
  border-radius: var(--radius);
}
.skeleton-text { height: 14px; margin-bottom: 8px; }
.skeleton-text:last-child { width: 60%; }
.skeleton-card { height: 140px; border-radius: var(--radius-lg); }
.skeleton-stat { height: 80px; border-radius: var(--radius-lg); }

/* ---------------------------------------------------------------- buttons */

.btn-primary, .btn-ghost {
  display: inline-flex; align-items: center; justify-content: center;
  font-weight: 600; border-radius: var(--radius); padding: 10px 20px;
  font-size: 14px; font-family: var(--font); cursor: pointer; border: none;
  transition: transform var(--transition-fast), box-shadow var(--transition-med), background var(--transition-fast);
  text-decoration: none;
}
.btn-primary {
  background: var(--accent); color: var(--on-accent);
  box-shadow: 0 2px 8px rgba(102, 194, 180, 0.35);
}
.btn-primary:hover {
  background: var(--accent-hover);
  box-shadow: 0 4px 16px rgba(102, 194, 180, 0.45);
  transform: translateY(-1px);
}
.btn-primary:active { transform: translateY(1px); box-shadow: 0 1px 4px rgba(102, 194, 180, 0.3); }
.btn-primary:disabled { opacity: .45; cursor: not-allowed; transform: none; }

.btn-ghost {
  background: var(--surface); color: var(--text);
  border: 1px solid var(--border);
}
.btn-ghost:hover { background: var(--bg-alt); border-color: var(--border-strong); transform: translateY(-1px); }
.btn-ghost:active { transform: translateY(1px); }

.btn-sm { padding: 6px 12px; font-size: 12px; }
.btn-danger:hover { border-color: var(--rose); color: var(--rose); background: var(--rose-soft); }

.btn-secondary {
  background: var(--secondary); color: var(--on-secondary);
}
.btn-secondary:hover { filter: brightness(1.05); transform: translateY(-1px); }

.icon-btn {
  background: transparent; border: none; color: var(--text-muted);
  width: 36px; height: 36px; border-radius: var(--radius); cursor: pointer;
  display: grid; place-items: center; font-family: var(--font);
  transition: background var(--transition-fast), color var(--transition-fast);
}
.icon-btn:hover { color: var(--text); background: var(--accent-soft); }

/* ---------------------------------------------------------------- focus */

:focus-visible {
  outline: 2px solid var(--accent-deep);
  outline-offset: 2px;
}

/* Custom controls: match each hover language so keyboard users get the
 * same affordance as pointer users. */
.sidenav-item:focus-visible {
  outline: 2px solid var(--accent-deep);
  outline-offset: -2px;
  background: var(--accent-soft);
  color: var(--text);
}
.rating-btn:focus-visible {
  outline: 2px solid var(--accent-deep);
  outline-offset: 2px;
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}
.quiz-opt:focus-visible {
  outline: 2px solid var(--accent-deep);
  outline-offset: 2px;
  border-color: var(--accent);
}
.qcard:focus-visible,
.deck-item:focus-visible,
.review-card:focus-visible {
  outline: 2px solid var(--accent-deep);
  outline-offset: 2px;
}