:root {
    /* Color: foundations */
    --color-background: #f7f9fa;
    --color-surface: #ffffff;
    --color-surface-secondary: #f1f5f9;
    --color-surface-subtle: #f8fafc;
    --color-border: #e2e8f0;
    --color-border-strong: #cbd5e1;

    /* Color: brand and text */
    --color-primary: #0f766e;
    --color-primary-hover: #0d6862;
    --color-primary-active: #0b5d57;
    --color-primary-light: #ccfbf1;
    --color-primary-soft: #f0fdfa;
    --color-text-primary: #0f172a;
    --color-text-secondary: #475569;
    --color-text-muted: #64748b;
    --color-text-disabled: #94a3b8;
    --color-text-inverse: #ffffff;

    /* Color: semantic states */
    --color-success: #237a57;
    --color-success-bg: #ecfdf5;
    --color-success-border: #a7f3d0;
    --color-warning: #9a6700;
    --color-warning-bg: #fffbeb;
    --color-warning-border: #fde68a;
    --color-danger: #b42318;
    --color-danger-hover: #912018;
    --color-danger-bg: #fff5f5;
    --color-danger-border: #fecaca;
    --color-info: #2563a6;
    --color-info-bg: #eff6ff;
    --color-info-border: #bfdbfe;

    /* Role accents: used only for small navigation and identity cues. */
    --role-accent: #2dd4bf;
    --role-accent-soft: rgba(45, 212, 191, 0.16);
    --role-platform: #0d9488;
    --role-consulting: #3182ce;
    --role-nurse: #7c5ac7;
    --role-company: #c66a24;
    --role-employee: #d66370;

    /* Typography */
    --font-sans: Inter, "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", system-ui, -apple-system, sans-serif;
    --font-size-caption: 0.75rem;
    --font-size-small: 0.8125rem;
    --font-size-body: 0.875rem;
    --font-size-body-lg: 0.9375rem;
    --font-size-card-title: 1rem;
    --font-size-section-title: 1.125rem;
    --font-size-page-title: 1.5rem;
    --font-size-display: 2rem;
    --font-weight-regular: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    --line-height-tight: 1.3;
    --line-height-body: 1.6;
    --line-height-relaxed: 1.75;

    /* Spacing: 4px base unit */
    --space-0: 0;
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;

    /* Shape and elevation */
    --radius-xs: 0.25rem;
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-pill: 999px;
    --border-width: 1px;
    --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06);
    --shadow-modal: 0 18px 48px rgba(15, 23, 42, 0.16);
    --focus-ring: 0 0 0 3px rgba(15, 118, 110, 0.22);

    /* Layout */
    --sidebar-width: 15rem;
    --sidebar-collapsed-width: 4rem;
    --topbar-height: 0rem;
    --workspace-max-width: 100rem;
    --drawer-width: 32rem;
    --content-gutter: clamp(1rem, 2.4vw, 2.5rem);

    /* Motion */
    --duration-fast: 120ms;
    --duration-default: 180ms;
    --easing-standard: cubic-bezier(0.2, 0, 0, 1);

    /* Z-index */
    --z-base: 0;
    --z-sticky: 100;
    --z-dropdown: 1000;
    --z-overlay: 1040;
    --z-drawer: 1050;
    --z-modal: 1060;
    --z-toast: 1080;

    /* Bootstrap-compatible breakpoint references (documentation / JS only). */
    --breakpoint-sm: 576px;
    --breakpoint-md: 768px;
    --breakpoint-lg: 992px;
    --breakpoint-xl: 1200px;
    --breakpoint-xxl: 1400px;
}