* { box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', 'PingFang SC', 'Microsoft YaHei', sans-serif; margin: 0; padding: 24px; background: #f3f4f6; }
.container { max-width: 1100px; margin: 0 auto; background: #fff; border-radius: 12px; box-shadow: 0 10px 30px rgba(0,0,0,.06); overflow: hidden; }
.header { background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); color: #fff; padding: 28px 32px; }
.header h1 { margin: 0 0 6px; font-size: 24px; }
.header p { margin: 0; opacity: .9; }
.main { padding: 28px 32px; }
.section { margin-bottom: 28px; }
.section h3 { margin: 0 0 12px; font-size: 18px; color: #1f2937; }
.card { border: 1px solid #e5e7eb; border-radius: 10px; padding: 16px; background: #fafafa; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 12px; }
.btn { display: inline-block; padding: 10px 18px; border-radius: 8px; border: 0; cursor: pointer; font-weight: 600; color: #fff; background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); }
.btn.secondary { background: #e5e7eb; color: #111827; }
.btn:disabled { opacity: .6; cursor: not-allowed; }
.row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
label { display: block; margin-bottom: 6px; color: #374151; font-size: 14px; }
input, textarea, select { width: 100%; padding: 10px 12px; border: 1px solid #e5e7eb; border-radius: 8px; outline: none; font-size: 14px; background: #fff; }
.list-item { border: 1px solid #e5e7eb; border-radius: 10px; padding: 14px; background: #fff; cursor: pointer; }
.list-item:hover { border-color: #667eea; background: #f5f7ff; }
.list-item.selected { border-color: #667eea; background: #eef2ff; }
.video-item { cursor: pointer; transition: border-color .15s ease, background .15s ease, box-shadow .15s ease; }
.video-item:hover { border-color: #667eea; background: #f5f7ff; box-shadow: 0 2px 8px rgba(102,126,234,.15); }
.video-item.selected { border-color: #667eea; background: #eef2ff; box-shadow: 0 4px 12px rgba(102,126,234,.25); }
.muted { color: #6b7280; font-size: 13px; }
.loading { text-align: center; color: #4f46e5; }
.error { color: #b91c1c; background: #fef2f2; border: 1px solid #fecaca; padding: 10px 12px; border-radius: 8px; }
.result { display: none; margin-top: 16px; border-top: 1px solid #e5e7eb; padding-top: 16px; }
.result.show { display: block; }
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 768px) { .row, .two-col { grid-template-columns: 1fr; } }