:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --bg-color: #f8fafc;
  --card-bg: #ffffff;
  --text-main: #1e293b;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --danger: #ef4444;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; background-color: var(--bg-color); color: var(--text-main); line-height: 1.5; }
a { text-decoration: none; color: inherit; cursor: pointer; }

header { background: var(--card-bg); border-bottom: 1px solid var(--border-color); position: sticky; top: 0; z-index: 100; }
.nav-container { max-width: 900px; margin: 0 auto; padding: 0.75rem 1rem; display: flex; justify-content: space-between; align-items: center; }
.nav-brand { font-weight: 700; font-size: 1.25rem; color: var(--primary); }
.nav-links { display: flex; gap: 1rem; align-items: center; font-size: 0.9rem; }
.nav-links a { padding: 0.35rem 0.75rem; border-radius: 0.375rem; color: var(--text-muted); }
.nav-links a:hover { color: var(--primary); background: #eff6ff; }

main { max-width: 900px; margin: 1.5rem auto; padding: 0 1rem; }
.card { background: var(--card-bg); border: 1px solid var(--border-color); border-radius: 0.5rem; padding: 1.25rem; margin-bottom: 1rem; }

button { cursor: pointer; font-family: inherit; }
.btn { background: var(--primary); color: white; border: none; padding: 0.5rem 1rem; border-radius: 0.375rem; font-size: 0.9rem; font-weight: 500; }
.btn:hover { background: var(--primary-hover); }
.btn-secondary { background: #e2e8f0; color: var(--text-main); }
.btn-danger { background: var(--danger); color: white; }
.btn-disabled-media { background: #cbd5e1 !important; color: #94a3b8 !important; cursor: not-allowed !important; opacity: 0.7; }

input, textarea, select { width: 100%; padding: 0.5rem 0.75rem; border: 1px solid var(--border-color); border-radius: 0.375rem; font-size: 0.95rem; margin-top: 0.25rem; margin-bottom: 0.75rem; }
input:focus, textarea:focus, select:focus { outline: none; border-color: var(--primary); }