/* ========== CSS Variables ========== */
:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafb;
  --bg-card: #ffffff;
  --bg-nav: rgba(255,255,255,0.92);
  --text-primary: #1a1a2e;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --color-accent: #0ea5e9;
  --color-accent-deep: #0369a1;
  --color-accent-glow: #38bdf8;
  --color-purple: #7c3aed;
  --color-purple-glow: #a78bfa;
  --border-color: #e8ecf0;
  --border-light: #f1f5f9;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 2px 8px rgba(0,0,0,0.06), 0 1px 3px rgba(0,0,0,0.04);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.08), 0 2px 8px rgba(0,0,0,0.04);
  --shadow-hover: 0 8px 30px rgba(14,165,233,0.12), 0 2px 8px rgba(0,0,0,0.06);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
  --transition-fast: 0.18s ease;
  --transition-normal: 0.25s ease;
  --max-width: 1320px;
}

[data-theme="dark"] {
  --bg-primary: #0b1120;
  --bg-secondary: #111827;
  --bg-card: #1a2332;
  --bg-nav: rgba(11,17,32,0.92);
  --text-primary: #e2e8f0;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --border-color: #1e293b;
  --border-light: #1a2332;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 2px 8px rgba(0,0,0,0.3);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.4);
  --shadow-hover: 0 8px 30px rgba(14,165,233,0.18), 0 2px 8px rgba(0,0,0,0.3);
}

/* ========== Reset & Base ========== */
*,*::before,*::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background var(--transition-normal), color var(--transition-normal);
}
a { text-decoration: none; color: inherit; }
ul,ol { list-style: none; }
img { max-width: 100%; display: block; }
button { cursor: pointer; border: none; background: none; font-family: inherit; }
input { font-family: inherit; border: none; outline: none; background: none; }