/* Design tokens — Luyện Đề
   Màu nhấn xanh lam; xanh lá = đúng; đỏ = sai; vàng = đánh dấu. Sáng/tối đầy đủ. */
:root {
  color-scheme: light;
  /* Nền & bề mặt */
  --bg: #f4f6fa;
  --bg-sunken: #eceff5;
  --surface: #ffffff;
  --surface-2: #f8f9fc;
  --surface-hover: #f1f4fa;
  --border: #dde2ec;
  --border-strong: #c5ccda;
  /* Chữ */
  --text: #151a26;
  --text-2: #475067;
  --text-3: #6b7489;
  --text-inverse: #ffffff;
  /* Nhấn */
  --primary: #2458d6;
  --primary-hover: #1c49b8;
  --primary-soft: #e8efff;
  --primary-soft-2: #d4e1ff;
  --on-primary: #ffffff;
  --focus: #2458d6;
  /* Trạng thái */
  --success: #16794a;
  --success-strong: #12a15c;
  --success-soft: #e3f6ec;
  --success-border: #8fd6b1;
  --danger: #c02a2a;
  --danger-strong: #dc3b3b;
  --danger-soft: #fdecec;
  --danger-border: #f0a9a9;
  --warning: #8a5a00;
  --warning-strong: #e9a310;
  --warning-soft: #fff5d6;
  --warning-border: #f1cf73;
  --info-soft: #eef2f8;
  /* Typography */
  --font: "Segoe UI", "Inter", system-ui, -apple-system, "Roboto", "Helvetica Neue", "Noto Sans", Arial, sans-serif;
  --font-mono: "Cascadia Mono", "Consolas", "SFMono-Regular", Menlo, monospace;
  --fs-xs: 0.75rem;
  --fs-sm: 0.875rem;
  --fs-md: 1rem;
  --fs-lg: 1.125rem;
  --fs-xl: 1.375rem;
  --fs-2xl: 1.75rem;
  --fs-3xl: 2.5rem;
  --fs-question: 1.125rem;   /* ~18px */
  --lh-tight: 1.3;
  --lh: 1.5;
  --lh-read: 1.65;
  /* Khoảng cách (4px) */
  --s1: 4px; --s2: 8px; --s3: 12px; --s4: 16px; --s5: 20px; --s6: 24px; --s8: 32px; --s10: 40px; --s12: 48px;
  /* Bo góc */
  --r-sm: 6px; --r-md: 10px; --r-lg: 14px; --r-xl: 20px; --r-full: 999px;
  /* Đổ bóng */
  --shadow-1: 0 1px 2px rgba(16, 24, 40, .06), 0 1px 3px rgba(16, 24, 40, .06);
  --shadow-2: 0 4px 12px rgba(16, 24, 40, .08), 0 1px 3px rgba(16, 24, 40, .06);
  --shadow-3: 0 16px 40px rgba(16, 24, 40, .16);
  /* Chuyển động */
  --ease: cubic-bezier(.2, .7, .2, 1);
  --t-fast: 120ms;
  --t: 180ms;
  /* Kích thước */
  --tap: 44px;
  --header-h: 60px;
  --content-max: 1440px;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0e131d;
  --bg-sunken: #0a0e16;
  --surface: #161c28;
  --surface-2: #1b2231;
  --surface-hover: #202939;
  --border: #283246;
  --border-strong: #3a465e;
  --text: #e8ecf4;
  --text-2: #b3bccd;
  --text-3: #8d97ab;
  --text-inverse: #0e131d;
  --primary: #6d97ff;
  --primary-hover: #8aacff;
  --primary-soft: #1b2744;
  --primary-soft-2: #243560;
  --on-primary: #0b1020;
  --focus: #8aacff;
  --success: #5fd49a;
  --success-strong: #2fbf78;
  --success-soft: #11291f;
  --success-border: #22643f;
  --danger: #ff8a8a;
  --danger-strong: #f05d5d;
  --danger-soft: #331618;
  --danger-border: #7a3035;
  --warning: #f6c65b;
  --warning-strong: #f0b429;
  --warning-soft: #2e2511;
  --warning-border: #6e5518;
  --info-soft: #1a2130;
  --shadow-1: 0 1px 2px rgba(0, 0, 0, .35);
  --shadow-2: 0 4px 14px rgba(0, 0, 0, .35);
  --shadow-3: 0 18px 44px rgba(0, 0, 0, .5);
}

:root[data-fontscale="lg"] { --fs-question: 1.25rem; }
:root[data-fontscale="sm"] { --fs-question: 1.0625rem; }

@media (prefers-reduced-motion: reduce) {
  :root { --t-fast: 0ms; --t: 0ms; }
  *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important; scroll-behavior: auto !important; }
}