:root {
  --bg: #f4f6fb;
  --surface: #ffffff;
  --border: #e6eaf2;
  --text: #1e293b;
  --text-soft: #64748b;
  --primary: #2563eb;
  --primary-light: #eff6ff;
  --grad: linear-gradient(135deg, #2563eb 0%, #7c3aed 50%, #f97316 100%);
  --success: #16a34a;
  --warning: #f59e0b;
  --danger: #ef4444;
}
[data-theme="dark"] {
  --bg: #0f1420;
  --surface: #1a2030;
  --border: #2a3346;
  --text: #e6eaf2;
  --text-soft: #94a3b8;
  --primary-light: #1e2a44;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, 'SF Pro Display', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  background: var(--bg); color: var(--text); line-height: 1.6; font-size: 15px;
  -webkit-font-smoothing: antialiased;
}
button { font-family: inherit; cursor: pointer; border: none; }
input, textarea { font-family: inherit; }
.btn { background: var(--primary); color: #fff; border-radius: 10px; padding: 10px 18px; font-weight: 600; transition: .15s; }
.btn:hover { filter: brightness(1.08); }
.btn-ghost { background: transparent; color: var(--text-soft); border: 1px solid var(--border); }
.btn-ghost:hover { background: var(--primary-light); color: var(--primary); }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: 16px; box-shadow: 0 2px 12px rgba(0,0,0,.04); }