:root {
  --color-bg: #ffffff;
  --color-bg-secondary: #f6f9fd;
  --color-bg-tertiary: #eaf1f8;
  --color-surface: #ffffff;
  --color-text: #18324a;
  --color-text-secondary: #58708a;
  --color-text-muted: #7890a8;
  --color-border: #dce7f1;
  --color-border-hover: #b9cee1;

  --color-primary: #2563a8;
  --color-primary-light: #e8f1fb;
  --color-primary-dark: #1d4f87;
  --color-primary-hover: #1d4f87;

  --color-signed: #3c82c6;
  --color-algebra: #4384bb;
  --color-equation: #5c78b6;
  --color-proportion: #607bb0;

  --color-j2-algebra: #2879b8;
  --color-j2-equation: #527fba;
  --color-j2-angles: #3d90bf;
  --color-j2-congruence: #6c89bc;
  --color-j2-linear: #2476bb;
  --color-j2-probability: #6375ad;
  --color-j2-stats: #278aaf;

  --color-j3-expression: #446fa8;
  --color-j3-sqrt: #647ab3;
  --color-j3-quadratic: #2376ba;
  --color-j3-similar: #6682b3;
  --color-j3-circle: #258aa9;
  --color-j3-pythagoras: #3684ad;
  --color-j3-quadfunc: #355a7b;
  --color-j3-survey: #72889d;
  --color-high-school: #7b5cb8;

  --color-success: #2f8a72;
  --color-warning: #bd7a26;
  --color-error: #c95757;
  --color-info: #3184c4;

  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  --font-sans: 'Noto Sans JP', 'Hiragino Sans', 'Hiragino Kaku Gothic ProN', 'Yu Gothic', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;

  --shadow-sm: 0 1px 2px rgba(32, 77, 119, 0.05);
  --shadow-md: 0 4px 10px rgba(32, 77, 119, 0.07);
  --shadow-lg: 0 10px 25px rgba(32, 77, 119, 0.10);
  --shadow-xl: 0 20px 40px rgba(32, 77, 119, 0.13);

  --max-width: 960px;
  --header-height: 60px;

  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 400ms ease;

  --z-header: 100;
  --z-modal: 200;
  --z-toast: 300;
}