:root {
  --color-bg: #f5f6f8;
  --color-surface: #ffffff;
  --color-border: #e0e2e7;
  --color-text: #1c1f26;
  --color-muted: #6b7280;
  --color-primary: #4f46e5;
  --color-primary-hover: #4338ca;
  --color-danger: #dc2626;
  --color-danger-bg: #fee2e2;
  --color-success: #16a34a;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.06);
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #14161c;
    --color-surface: #1d2028;
    --color-border: #2c303a;
    --color-text: #e9eaee;
    --color-muted: #9aa0ab;
    --color-primary: #818cf8;
    --color-primary-hover: #6366f1;
    --color-danger: #f87171;
    --color-danger-bg: #3f1d1d;
    --color-success: #4ade80;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.4), 0 1px 2px rgba(0, 0, 0, 0.3);
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.site-header {
  padding: 40px 0 28px;
  text-align: center;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-surface);
}

.site-header h1 {
  margin: 0 0 8px;
  font-size: 2rem;
}

.subtitle {
  margin: 0;
  color: var(--color-muted);
  font-size: 1.05rem;
}

.btn {
  font-size: 0.85rem;
  font-weight: 600;
  padding: 8px 14px;
  border-radius: 8px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
}
.btn-primary:hover { background: var(--color-primary-hover); }

.btn-secondary {
  background: transparent;
  color: var(--color-text);
  border-color: var(--color-border);
}
.btn-secondary:hover { border-color: var(--color-muted); }

.hidden { display: none !important; }

.site-footer {
  text-align: center;
  padding: 24px 0;
  color: var(--color-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--color-border);
}