/* ═══════════════════════════════════════════════════════════════════════════
   main.css — Design System for VocabStudy
   
   Token layers:
     1. Root variables (colors, typography, spacing, shadows)
     2. Reset & base
     3. Shared components (buttons, cards, badges, progress rings, modals)
   ═══════════════════════════════════════════════════════════════════════════ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;600&display=swap');

/* ─── 1. Design Tokens ────────────────────────────────────────────────────── */
:root {
  /* Base palette */
  --clr-bg-deep: #080f0b;
  --clr-bg-base: #0d1a13;
  --clr-bg-surface: #132019;
  --clr-bg-raised: #192a1f;
  --clr-bg-hover: #1f3426;

  /* Accent — Emerald Green */
  --clr-accent: #10b981;
  --clr-accent-light: #34d399;
  --clr-accent-dim: rgba(16, 185, 129, 0.15);
  --clr-accent-glow: rgba(16, 185, 129, 0.4);

  /* Semantic */
  --clr-correct: #4ade80;
  --clr-correct-dim: rgba(74, 222, 128, 0.15);
  --clr-correct-glow: rgba(74, 222, 128, 0.4);

  --clr-close: #f59e0b;
  --clr-close-dim: rgba(245, 158, 11, 0.15);
  --clr-close-glow: rgba(245, 158, 11, 0.35);

  --clr-wrong: #ef4444;
  --clr-wrong-dim: rgba(239, 68, 68, 0.15);
  --clr-wrong-glow: rgba(239, 68, 68, 0.4);

  --clr-xp: #fbbf24;

  /* Mastery colors */
  --clr-mastery--1: #ef4444;
  /* Missed */
  --clr-mastery-0: #374151;
  /* New */
  --clr-mastery-1: #3b82f6;
  /* Learning */
  --clr-mastery-2: #8b5cf6;
  /* Familiar */
  --clr-mastery-3: #22c55e;
  /* Mastered */

  /* Text */
  --clr-text-primary: #f1f5f9;
  --clr-text-secondary: #94a3b8;
  --clr-text-muted: #4b5563;
  --clr-text-inverse: #080f0b;

  /* Borders */
  --clr-border: rgba(255, 255, 255, 0.06);
  --clr-border-focus: rgba(16, 185, 129, 0.5);

  /* Typography */
  --font-sans: 'Inter', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;

  /* Spacing scale */
  --sp-1: 4px;
  --sp-2: 8px;
  --sp-3: 12px;
  --sp-4: 16px;
  --sp-5: 20px;
  --sp-6: 24px;
  --sp-8: 32px;
  --sp-10: 40px;
  --sp-12: 48px;
  --sp-16: 64px;

  /* Border radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.6);
  --shadow-glow-accent: 0 0 24px var(--clr-accent-glow);
  --shadow-glow-correct: 0 0 24px var(--clr-correct-glow);
  --shadow-glow-wrong: 0 0 24px var(--clr-wrong-glow);

  /* Transitions */
  --transition-fast: 120ms ease;
  --transition-base: 220ms ease;
  --transition-slow: 400ms ease;
}

/* ─── 2. Reset & Base ─────────────────────────────────────────────────────── */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--clr-bg-deep);
  color: var(--clr-text-primary);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

a {
  color: var(--clr-accent-light);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--clr-text-primary);
}

/* ─── 3. Shared Components ────────────────────────────────────────────────── */

/* ··· Buttons ··· */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: var(--sp-3) var(--sp-5);
  border: none;
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition:
    background var(--transition-fast),
    transform var(--transition-fast),
    box-shadow var(--transition-fast);
  user-select: none;
  white-space: nowrap;
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: linear-gradient(135deg, var(--clr-accent), #059669);
  color: #fff;
  box-shadow: 0 4px 14px var(--clr-accent-glow);
}

.btn-primary:hover {
  box-shadow: 0 6px 20px var(--clr-accent-glow);
  filter: brightness(1.08);
}

.btn-ghost {
  background: transparent;
  color: var(--clr-text-secondary);
  border: 1px solid var(--clr-border);
}

.btn-ghost:hover {
  background: var(--clr-bg-hover);
  color: var(--clr-text-primary);
}

.btn-icon {
  width: 38px;
  height: 38px;
  padding: 0;
  border-radius: var(--radius-md);
  justify-content: center;
}

.btn-lg {
  padding: var(--sp-4) var(--sp-8);
  font-size: 1rem;
  border-radius: var(--radius-lg);
}

/* ··· Cards ··· */
.card {
  background: var(--clr-bg-surface);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-lg);
  padding: var(--sp-6);
  transition: border-color var(--transition-base), box-shadow var(--transition-base), transform var(--transition-base);
}

.card:hover {
  border-color: rgba(16, 185, 129, 0.25);
  box-shadow: var(--shadow-md);
}

.card.interactive {
  cursor: pointer;
}

.card.interactive:hover {
  transform: translateY(-2px);
}

/* ··· Badges ··· */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 10px;
  border-radius: var(--radius-full);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.badge-accent {
  background: var(--clr-accent-dim);
  color: var(--clr-accent-light);
}

.badge-correct {
  background: var(--clr-correct-dim);
  color: var(--clr-correct);
}

.badge-close {
  background: var(--clr-close-dim);
  color: var(--clr-close);
}

.badge-wrong {
  background: var(--clr-wrong-dim);
  color: var(--clr-wrong);
}

/* ··· Mastery badges ··· */
.mastery-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 10px;
  border-radius: var(--radius-full);
  font-size: 0.72rem;
  font-weight: 600;
}

.mastery--1 {
  background: rgba(239, 68, 68, 0.15);
  color: #f87171;
}

.mastery-0 {
  background: rgba(55, 65, 81, 0.5);
  color: var(--clr-text-muted);
}

.mastery-1 {
  background: rgba(59, 130, 246, 0.15);
  color: #60a5fa;
}

.mastery-2 {
  background: rgba(139, 92, 246, 0.15);
  color: #a78bfa;
}

.mastery-3 {
  background: rgba(34, 197, 94, 0.15);
  color: #4ade80;
}

/* ··· Progress Ring (SVG-based) ··· */
.progress-ring {
  display: block;
  transform: rotate(-90deg);
}

.progress-ring__track {
  fill: none;
  stroke: var(--clr-bg-raised);
}

.progress-ring__fill {
  fill: none;
  stroke: var(--clr-accent);
  stroke-linecap: round;
  transition: stroke-dashoffset 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ··· Divider ··· */
.divider {
  height: 1px;
  background: var(--clr-border);
  margin: var(--sp-6) 0;
}

/* ··· Skeleton shimmer ··· */
.skeleton {
  background: linear-gradient(90deg,
      var(--clr-bg-surface) 25%,
      var(--clr-bg-raised) 50%,
      var(--clr-bg-surface) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius-md);
}

@keyframes shimmer {
  0% {
    background-position: 200% 0;
  }

  100% {
    background-position: -200% 0;
  }
}

/* ··· Stat pill ··· */
.stat-pill {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: var(--sp-3) var(--sp-5);
  background: var(--clr-bg-raised);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-md);
}

.stat-pill .stat-value {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--clr-text-primary);
  line-height: 1;
}

.stat-pill .stat-label {
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--clr-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

/* ··· Modal backdrop ··· */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-base);
}

.modal-backdrop.open {
  opacity: 1;
  pointer-events: all;
}

.modal {
  background: var(--clr-bg-surface);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-xl);
  padding: var(--sp-8);
  max-width: 480px;
  width: calc(100% - var(--sp-8));
  box-shadow: var(--shadow-lg);
  transform: translateY(16px) scale(0.97);
  transition: transform var(--transition-base);
}

.modal-backdrop.open .modal {
  transform: translateY(0) scale(1);
}

/* ··· Tooltip ··· */
[data-tooltip] {
  position: relative;
}

[data-tooltip]::after {
  content: attr(data-tooltip);
  position: absolute;
  top: calc(100% + 6px);
  left: 50%;
  transform: translateX(-50%);
  background: var(--clr-bg-deep);
  color: var(--clr-text-primary);
  font-size: 0.75rem;
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: opacity var(--transition-fast);
  border: 1px solid var(--clr-accent-dim);
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.9);
  z-index: 1000;
}

[data-tooltip]:hover::after {
  opacity: 1;
}

/* ··· Scrollbar ··· */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: var(--clr-bg-deep);
}

::-webkit-scrollbar-thumb {
  background: var(--clr-bg-raised);
  border-radius: 99px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--clr-bg-hover);
}

/* ··· Utility classes ··· */
.text-primary {
  color: var(--clr-text-primary);
}

.text-secondary {
  color: var(--clr-text-secondary);
}

.text-muted {
  color: var(--clr-text-muted);
}

.text-accent {
  color: var(--clr-accent-light);
}

.text-correct {
  color: var(--clr-correct);
}

.text-wrong {
  color: var(--clr-wrong);
}

.text-close {
  color: var(--clr-close);
}

.text-xp {
  color: var(--clr-xp);
}

.font-mono {
  font-family: var(--font-mono);
}

.font-bold {
  font-weight: 700;
}

.font-medium {
  font-weight: 500;
}

.flex {
  display: flex;
}

.flex-col {
  flex-direction: column;
}

.items-center {
  align-items: center;
}

.justify-between {
  justify-content: space-between;
}

.gap-1 {
  gap: var(--sp-1);
}

.gap-2 {
  gap: var(--sp-2);
}

.gap-3 {
  gap: var(--sp-3);
}

.gap-4 {
  gap: var(--sp-4);
}

.gap-6 {
  gap: var(--sp-6);
}

.w-full {
  width: 100%;
}

.text-center {
  text-align: center;
}

.mt-auto {
  margin-top: auto;
}