:root{color:#eef2ff;background:#070b16;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}*{box-sizing:border-box}body{background:#0b1020;min-width:320px;min-height:100vh;margin:0}button,video,select{font:inherit}button{color:inherit}.page-shell{min-height:100vh;padding:22px}.app-shell{background:#0d1426;border:1px solid #ffffff17;border-radius:24px;width:min(100%,1320px);margin:auto;overflow:hidden}.topbar{border-bottom:1px solid #ffffff14;justify-content:space-between;align-items:center;gap:20px;padding:20px 22px;display:flex}.eyebrow,.section-title{color:#9ba8ff;letter-spacing:.13em;text-transform:uppercase;margin:0;font-size:.75rem;font-weight:800}h1,h2{margin:0}h1{margin-top:6px;font-size:clamp(1.45rem,3vw,2.15rem)}h2{margin-top:7px;font-size:clamp(1.2rem,2vw,1.65rem)}.status{color:#c8d0ff;background:#7d8cff1f;border:1px solid #7d8cff3d;border-radius:999px;padding:8px 12px;font-size:.82rem}.workspace{grid-template-columns:260px minmax(0,1fr);min-height:620px;display:grid}.sidebar{border-right:1px solid #ffffff14;padding:20px 14px}.subject-list,.video-list{gap:8px;margin-top:13px;display:grid}.subject-button,.video-item{cursor:pointer;background:0 0;border:1px solid #0000;width:100%}.subject-button{text-align:left;border-radius:12px;justify-content:space-between;align-items:center;gap:12px;padding:13px 12px;display:flex}.subject-button span{font-weight:700}.subject-button small{color:#7f8aa9;white-space:nowrap}.subject-button.active,.video-item.active{background:#7888ff1f;border-color:#7888ff3d}.content-area{min-width:0;padding:22px}.content-header{margin-bottom:14px}.video-frame{aspect-ratio:16/9;background:#000;border:1px solid #ffffff14;border-radius:18px;overflow:hidden}.video-frame video,.empty-player{width:100%;height:100%}.video-frame video{object-fit:contain;background:#000;display:block}.empty-player{color:#8792ae;place-items:center;display:grid}.video-library{margin-top:22px}.video-item{text-align:left;background:#ffffff06;border-color:#ffffff12;border-radius:13px;grid-template-columns:48px minmax(0,1fr) 34px;align-items:center;gap:10px;padding:12px;display:grid}.video-number{color:#7f8aa9;font-size:.78rem;font-weight:800}.video-title{font-weight:700}.play-mark{color:#9ba8ff;text-align:center}.mobile-subject-picker{display:none}.error-box{color:#ffd0d0;border:1px solid #ff787840;border-radius:12px;margin:16px 22px 0;padding:12px 14px}@media (width<=820px){.page-shell{padding:10px}.app-shell{border-radius:18px}.topbar{padding:16px}.workspace{min-height:0;display:block}.sidebar{display:none}.content-area{padding:14px}.mobile-subject-picker{gap:7px;margin-bottom:18px;display:grid}.mobile-subject-picker label{color:#8d98b5;font-size:.78rem;font-weight:700}.mobile-subject-picker select{color:#eef2ff;background:#11182a;border:1px solid #ffffff1a;border-radius:12px;width:100%;padding:12px 13px}}