:root {
  /* Brand and semantic colors */
  --color-brand-navy: #06285F;
  --color-brand-blue: #075BAD;
  --color-snow: #F4FAFF;
  --color-surface: #FFFFFF;
  --color-action: #FF704B;
  --color-brand-gold: #FFD334;
  --color-text-primary: var(--color-brand-navy);
  --color-text-secondary: #40566D;
  --color-text-inverse: #FFFFFF;
  --color-border: #B8C9D8;
  --color-surface-muted: #E8F2F8;
  --color-brand-blue-hover: #064A8D;
  --color-action-hover: #E85C38;
  --color-focus: #005FCC;
  --color-success: #1F7A4D;
  --color-warning: #8A5A00;
  --color-error: #B42318;
  --color-overlay: rgb(6 40 95 / 72%);
  --color-on-action: #33160E;

  /* Typography */
  --font-family-sans: "Noto Sans TC", "Microsoft JhengHei", system-ui, sans-serif;
  --font-family-serif: "Noto Serif TC", "Microsoft JhengHei", serif;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-md: 1.125rem;
  --font-size-lg: clamp(1.25rem, 1.15rem + 0.5vw, 1.5rem);
  --font-size-xl: clamp(1.5rem, 1.25rem + 1.25vw, 2.25rem);
  --font-size-2xl: clamp(2rem, 1.55rem + 2.25vw, 3.25rem);
  --font-weight-regular: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  --line-height-tight: 1.2;
  --line-height-heading: 1.35;
  --line-height-body: 1.7;
  --letter-spacing-tight: -0.015em;
  --letter-spacing-normal: 0;
  --letter-spacing-wide: 0.08em;

  /* Spacing */
  --space-0: 0;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --space-8: 4rem;
  --space-9: 6rem;
  --space-10: 8rem;

  /* Layout */
  --layout-content-max: 72rem;
  --layout-wide-max: 90rem;
  --layout-readable-max: 44rem;
  --layout-card-min: 17.5rem;
  --gutter-mobile: 1rem;
  --gutter-tablet: 1.5rem;
  --gutter-desktop: 2rem;

  /* Borders and radii */
  --border-width: 1px;
  --radius-small: 0.375rem;
  --radius-medium: 0.75rem;
  --radius-large: 1.25rem;
  --radius-pill: 999rem;

  /* Shadows */
  --shadow-card: 0 0.25rem 1rem rgb(6 40 95 / 10%);
  --shadow-elevated: 0 0.75rem 2rem rgb(6 40 95 / 16%);
  --shadow-overlay: 0 1.5rem 4rem rgb(6 40 95 / 28%);

  /* Layer order */
  --z-index-base: 0;
  --z-index-sticky: 100;
  --z-index-header: 200;
  --z-index-dropdown: 300;
  --z-index-overlay: 400;
  --z-index-modal: 500;

  /* Motion */
  --duration-fast: 120ms;
  --duration-normal: 220ms;
  --duration-slow: 360ms;
  --easing-standard: cubic-bezier(0.2, 0, 0, 1);
  --motion-press-distance: 1px;

  /* Touch and focus */
  --touch-target-min: 44px;
  --focus-ring-width: 3px;
  --focus-ring-offset: 3px;
  --focus-ring-shadow: 0 0 0 2px var(--color-surface), 0 0 0 5px var(--color-focus);
  --opacity-disabled: 0.55;
}