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

:root {
  --color-grammar: #818cf8;
  --color-vocabulary: #34d399;
  --color-expressions: #fbbf24;
  --color-pronunciation: #f87171;
  --color-bg: #0f172a;
  --color-surface: #1e293b;
  --color-surface-2: #273348;
  --color-border: #334155;
  --color-text: #f1f5f9;
  --color-text-muted: #94a3b8;
  --color-correct: #22c55e;
  --color-wrong: #ef4444;
  --color-accent: #818cf8;
  --color-accent-glow: rgba(129, 140, 248, 0.15);
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --radius: 12px;
  --radius-sm: 8px;
  --transition: 200ms ease;
  --shadow: 0 4px 24px rgba(0,0,0,0.4);
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  min-height: 100vh;
  line-height: 1.6;
}

a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── NAV ─────────────────────────────────────────── */
.nav {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 16px 24px;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  flex-wrap: wrap;
}

.nav-brand {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-accent);
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}

.nav-brand:hover { text-decoration: none; opacity: 0.85; }

.nav-sep { color: var(--color-border); user-select: none; }

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  list-style: none;
}

.breadcrumb li {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.breadcrumb li a {
  color: var(--color-text-muted);
  transition: color var(--transition);
}

.breadcrumb li a:hover { color: var(--color-text); text-decoration: none; }
.breadcrumb li.active { color: var(--color-text); }

/* ── BADGE ───────────────────────────────────────── */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 8px;
  border-radius: 99px;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.badge-1 { background: rgba(34,197,94,0.15); color: #22c55e; }
.badge-2 { background: rgba(251,191,36,0.15); color: #fbbf24; }
.badge-3 { background: rgba(239,68,68,0.15); color: #ef4444; }
.badge-grammar { background: rgba(129,140,248,0.15); color: var(--color-grammar); }
.badge-vocabulary { background: rgba(52,211,153,0.15); color: var(--color-vocabulary); }
.badge-expressions { background: rgba(251,191,36,0.15); color: var(--color-expressions); }
.badge-pronunciation { background: rgba(248,113,113,0.15); color: var(--color-pronunciation); }

/* ── BUTTON ──────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all var(--transition);
  text-decoration: none;
}

.btn-primary {
  background: var(--color-accent);
  color: #0f172a;
}
.btn-primary:hover { background: #a5b4fc; text-decoration: none; }

.btn-ghost {
  background: transparent;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
}
.btn-ghost:hover { background: var(--color-surface-2); color: var(--color-text); text-decoration: none; }

.btn-correct {
  background: rgba(34,197,94,0.15);
  color: var(--color-correct);
  border: 1px solid rgba(34,197,94,0.3);
}

.btn-wrong {
  background: rgba(239,68,68,0.15);
  color: var(--color-wrong);
  border: 1px solid rgba(239,68,68,0.3);
}

/* ── CARD ────────────────────────────────────────── */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
}

/* ── COMPARISON BLOCK ────────────────────────────── */
.comparison {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 8px 0;
}

@media (max-width: 640px) {
  .comparison { grid-template-columns: 1fr; }
}

.comparison-en, .comparison-pt {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  line-height: 1.5;
}

.comparison-en {
  background: rgba(129,140,248,0.08);
  border-left: 3px solid var(--color-grammar);
}

.comparison-pt {
  background: rgba(52,211,153,0.08);
  border-left: 3px solid var(--color-vocabulary);
}

.lang-label {
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 4px;
  opacity: 0.6;
}

/* ── UTILITY ─────────────────────────────────────── */
.text-muted { color: var(--color-text-muted); }
.text-sm { font-size: 0.875rem; }
.text-xs { font-size: 0.75rem; }
.font-mono { font-family: 'Fira Code', 'Cascadia Code', monospace; }
.mt-4 { margin-top: 16px; }
.mt-8 { margin-top: 32px; }
.mb-4 { margin-bottom: 16px; }
.flex { display: flex; }
.gap-2 { gap: 8px; }
.gap-4 { gap: 16px; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.flex-wrap { flex-wrap: wrap; }

/* ── SCROLLBAR ───────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--color-bg); }
::-webkit-scrollbar-thumb { background: var(--color-border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--color-text-muted); }