/* ============================================================
   Design Tokens — CSS Custom Properties
   ============================================================ */
:root {
  /* Colors */
  --color-primary: #6366F1;
  --color-primary-hover: #4F46E5;
  --color-primary-subtle: #EEF2FF;
  --color-accent: #F59E0B;
  --color-success: #10B981;
  --color-error: #EF4444;
  --color-warning: #F59E0B;
  --color-surface: #FFFFFF;
  --color-surface-alt: #F8FAFC;
  --color-bg: #F1F5F9;
  --color-text-primary: #0F172A;
  --color-text-secondary: #475569;
  --color-text-tertiary: #94A3B8;
  --color-border: #E2E8F0;
  --color-border-focus: #6366F1;

  /* Typography */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --font-sans: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-number: "Inter", -apple-system, "Segoe UI", monospace;

  /* Spacing (4px base) */
  --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;

  /* Radii */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.06), 0 2px 4px -2px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.06), 0 4px 6px -4px rgba(0,0,0,0.04);
  --shadow-glow: 0 0 0 3px rgba(99,102,241,0.15);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;
}
/* ============================================================
   Reset & Base
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  background: var(--color-bg);
  color: var(--color-text-primary);
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}

a { color: var(--color-primary); text-decoration: none; }
a:hover { color: var(--color-primary-hover); }

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

::selection {
  background: var(--color-primary-subtle);
  color: var(--color-primary);
}