:root{--bg:#0f1724;--panel:#071326;--accent:#5cc5ff;--muted:#9fb3c8;--text:#e6eef8;--card:#081220}
*{box-sizing:border-box}
html,body{height:100%;margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,"Helvetica Neue",Arial;color:var(--text);background:linear-gradient(180deg,#061021 0%,#071426 100%)}
header{display:flex;align-items:center;justify-content:space-between;padding:14px 20px;background:linear-gradient(90deg,rgba(255,255,255,0.02),transparent);backdrop-filter:blur(4px)}
header h1{margin:0;font-size:1.1rem}
nav a{color:var(--muted);margin-left:14px;text-decoration:none}
main{padding:18px 20px}
.layout{display:flex;gap:16px;align-items:flex-start}
.sidebar{width:220px}
.sidebar .panel{padding:12px;height:calc(100vh - 120px);overflow:auto}
.sidebar h2{margin:0 0 8px 0;font-size:0.95rem}
.sidebar ul{list-style:none;padding:0;margin:0}
.sidebar li{margin:6px 0}
.level-link{display:block;width:100%;text-align:left;padding:8px;border-radius:6px;border:0;background:transparent;color:var(--muted);cursor:pointer;font-weight:600}
.level-link.active{background:rgba(92,197,255,0.06);color:var(--accent)}
.content{flex:1}
.panel{background:var(--panel);padding:14px;border-radius:10px;margin-bottom:12px;box-shadow:0 3px 12px rgba(2,6,23,0.6)}
.search-row{display:flex;gap:8px;align-items:center;margin-bottom:12px}
.search-row input[type=text]{flex:1;padding:10px 12px;border-radius:8px;border:1px solid rgba(255,255,255,0.04);background:transparent;color:var(--text)}
.search-row select{padding:8px;border-radius:8px;border:1px solid rgba(255,255,255,0.04);background:transparent;color:var(--text)}
.table-wrap{overflow:auto;border-radius:8px}
table.levels-table{width:100%;border-collapse:collapse;background:linear-gradient(180deg,rgba(255,255,255,0.012),transparent)}
table.levels-table th,table.levels-table td{padding:12px 14px;border-bottom:1px solid rgba(255,255,255,0.02);text-align:left}
table.levels-table th{color:var(--muted);font-size:0.85rem;font-weight:600}
table.levels-table tr:hover td{background:rgba(255,255,255,0.01)}
.btn{display:inline-block;padding:8px 10px;border-radius:8px;background:var(--accent);color:#042;cursor:pointer;border:none}
.muted{color:var(--muted);font-size:0.9rem}
.video-modal{position:fixed;inset:0;background:rgba(0,0,0,0.7);display:flex;align-items:center;justify-content:center;z-index:1200}
.video-modal .inner{width:90%;max-width:960px;background:var(--card);padding:12px;border-radius:8px}
.video-modal iframe{width:100%;height:540px;border:0;border-radius:6px}
@media(max-width:900px){.layout{flex-direction:column}.sidebar{width:100%}.video-modal iframe{height:320px}}

/* small helpers reused */
.small{font-size:0.9rem}