:root {
  /* Base neutrals */
  --color-paper: #f7f5f2;
  --color-paper-deep: #ede9e3;
  --color-surface: #ffffff;
  --color-ink: #1a1814;

  /* Ink opacity scale */
  --color-ink-06: rgba(26, 24, 20, 0.06);
  --color-ink-12: rgba(26, 24, 20, 0.12);
  --color-ink-24: rgba(26, 24, 20, 0.24);
  --color-ink-40: rgba(26, 24, 20, 0.40);
  --color-ink-56: rgba(26, 24, 20, 0.56);
  --color-ink-72: rgba(26, 24, 20, 0.72);
  --color-ink-100: rgba(26, 24, 20, 1.00);

  /* Accent */
  --color-accent: #2e5c4f;
  --color-accent-dark: #1c3d33;
  --color-accent-soft: #d4e4e0;

  /* Semantic */
  --color-success: #2d7a4f;
  --color-warning: #b5730f;
  --color-danger: #b83232;
  --color-info: #2a5c8a;

  /* Type stack */
  --font-sans: "Noto Sans JP", "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Meiryo", sans-serif;
  --font-serif: "Noto Sans JP", "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Meiryo", sans-serif;
  --font-mono: "SFMono-Regular", "Consolas", "Liberation Mono", "Courier New", monospace;

  /* Type scale */
  --text-xs: 0.694rem;
  --text-sm: 0.833rem;
  --text-base: 1rem;
  --text-md: 1.125rem;
  --text-lg: 1.25rem;
  --text-xl: 1.5rem;
  --text-2xl: 1.875rem;
  --text-3xl: 2.25rem;
  --text-4xl: 3rem;
  --text-5xl: 3.75rem;

  /* Line-height */
  --leading-display: 1.15;
  --leading-heading: 1.4;
  --leading-body: 1.9;
  --leading-ui: 1.4;
  --leading-tight: 1.2;

  /* Letter-spacing */
  --tracking-ja: 0.08em;
  --tracking-upper: 0.14em;
  --tracking-display: 0.06em;

  /* Spacing scale (8px base) */
  --s-1: 4px;
  --s-2: 8px;
  --s-3: 12px;
  --s-4: 16px;
  --s-5: 20px;
  --s-6: 24px;
  --s-8: 32px;
  --s-10: 40px;
  --s-12: 48px;
  --s-14: 56px;
  --s-16: 64px;
  --s-20: 80px;
  --s-24: 96px;
  --s-28: 112px;
  --s-32: 128px;
  --s-36: 144px;
  --s-40: 160px;

  /* Borders */
  --border-hairline: 1px solid var(--color-ink-12);
  --border-strong: 1.5px solid var(--color-ink-72);
  --border-focus: 2px solid var(--color-accent);

  /* Radii */
  --radius-none: 0px;
  --radius-sm: 2px;
  --radius-md: 4px;
  --radius-lg: 8px;
  --radius-pill: 9999px;

  /* Shadows */
  --shadow-1: 0 1px 4px rgba(26, 24, 20, 0.08), 0 1px 2px rgba(26, 24, 20, 0.06);
  --shadow-2: 0 4px 16px rgba(26, 24, 20, 0.12), 0 2px 6px rgba(26, 24, 20, 0.08);

  /* Motion */
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --dur-micro: 80ms;
  --dur-small: 160ms;
  --dur-medium: 320ms;

  /* Layout */
  --max-w: 1120px;
  --gutter: clamp(16px, 4vw, 48px);
  --header-h: 64px;
}