:root {
  color-scheme: light dark;
  --bg: #0f1115;
  --bg-elevated: #171a21;
  --border: #2a2e38;
  --text: #e8eaed;
  --text-dim: #9aa1ad;
  --accent: #f0b429;
  --accent-dim: #8a6a1f;
  --danger: #e5484d;
  --success: #3fb950;
  --radius: 10px;
  --max-width: 1080px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, "Segoe UI", "Malgun Gothic", sans-serif;
  line-height: 1.5;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { max-width: var(--max-width); margin: 0 auto; padding: 0 16px; }

header.site-header {
  border-bottom: 1px solid var(--border);
  background: var(--bg-elevated);
}
header.site-header .bar {
  display: flex; align-items: center; justify-content: space-between;
  max-width: var(--max-width); margin: 0 auto; padding: 14px 16px;
}
.logo { font-size: 1.2rem; font-weight: 700; color: var(--text); }
.logo span { color: var(--accent); }
nav.main-nav { display: flex; gap: 16px; align-items: center; font-size: 0.95rem; }
nav.main-nav a { color: var(--text-dim); }
nav.main-nav a:hover { color: var(--text); }

.btn {
  display: inline-block; padding: 9px 16px; border-radius: var(--radius);
  border: 1px solid var(--border); background: var(--bg-elevated); color: var(--text);
  cursor: pointer; font-size: 0.9rem;
}
.btn:hover { border-color: var(--accent); }
.btn-primary { background: var(--accent); color: #1a1500; border: none; font-weight: 600; }
.btn-primary:hover { opacity: 0.9; }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }

.course-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin: 24px 0;
}
@media (max-width: 860px) { .course-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .course-grid { grid-template-columns: 1fr; } }

.course-card {
  background: var(--bg-elevated); border: 1px solid var(--border); border-radius: var(--radius);
  overflow: hidden; display: flex; flex-direction: column;
}
.course-card .thumb {
  aspect-ratio: 16/9; background: linear-gradient(135deg, #2a2e38, #171a21);
  display: flex; align-items: center; justify-content: center; color: var(--text-dim); font-size: 0.85rem;
}
.course-card .body { padding: 14px; display: flex; flex-direction: column; gap: 6px; flex: 1; }
.course-card .title { font-weight: 600; font-size: 1rem; }
.course-card .instructor { color: var(--text-dim); font-size: 0.85rem; }
.course-card .price { margin-top: auto; font-weight: 700; color: var(--accent); }

.card { background: var(--bg-elevated); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; }

.form-group { margin-bottom: 14px; }
.form-group label { display: block; margin-bottom: 6px; font-size: 0.9rem; color: var(--text-dim); }
.form-group input, .form-group textarea, .form-group select {
  width: 100%; padding: 10px 12px; border-radius: var(--radius); border: 1px solid var(--border);
  background: var(--bg); color: var(--text); font-size: 0.95rem;
}
.form-group input:focus, .form-group textarea:focus { outline: none; border-color: var(--accent); }

.tabs { display: flex; gap: 8px; margin-bottom: 18px; }
.tabs button {
  flex: 1; padding: 10px; border-radius: var(--radius); border: 1px solid var(--border);
  background: var(--bg); color: var(--text-dim); cursor: pointer;
}
.tabs button.active { background: var(--accent); color: #1a1500; border: none; font-weight: 600; }

.alert { padding: 10px 14px; border-radius: var(--radius); font-size: 0.9rem; margin-bottom: 14px; }
.alert-error { background: rgba(229, 72, 77, 0.15); color: var(--danger); border: 1px solid var(--danger); }
.alert-success { background: rgba(63, 185, 80, 0.15); color: var(--success); border: 1px solid var(--success); }

.lesson-list { list-style: none; padding: 0; margin: 0; }
.lesson-list li {
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 14px; border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 8px;
}
.badge { font-size: 0.75rem; padding: 2px 8px; border-radius: 999px; background: var(--bg); border: 1px solid var(--border); color: var(--text-dim); }
.badge.live { color: var(--danger); border-color: var(--danger); }

.empty-state { text-align: center; color: var(--text-dim); padding: 40px 0; }