:root{--bg: #eef1fb;--surface: #fff;--text: #1f2430;--muted: #737a92;--primary: #4f46e5;--primary-soft: #e9e8fd;--accent: #ffb020;--border: #e4e7f2;--shadow: 0 6px 24px rgba(79, 70, 229, .08);--radius: 16px}*{box-sizing:border-box}html,body{margin:0;padding:0}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,PingFang SC,Hiragino Sans GB,Microsoft YaHei,Helvetica Neue,Arial,sans-serif;background:radial-gradient(1200px 600px at 100% -10%,#e5e4ff 0%,transparent 60%),radial-gradient(900px 500px at -10% 20%,#ffe8c9 0%,transparent 55%),var(--bg);color:var(--text);-webkit-font-smoothing:antialiased;min-height:100vh;padding-bottom:calc(120px + env(safe-area-inset-bottom))}button{font-family:inherit}.app-loading{display:grid;place-items:center;height:100vh;color:var(--muted)}.app-header{position:sticky;top:0;z-index:20;background:#ffffffd1;-webkit-backdrop-filter:saturate(180%) blur(14px);backdrop-filter:saturate(180%) blur(14px);border-bottom:1px solid var(--border)}.brand{max-width:720px;margin:0 auto;padding:12px 16px;display:flex;align-items:center;gap:12px}.logo{width:42px;height:42px;border-radius:12px;display:grid;place-items:center;font-size:22px;flex:0 0 auto;background:linear-gradient(135deg,var(--primary),#7c6cf0);box-shadow:0 6px 16px #4f46e54d}.brand-text{min-width:0;flex:1}.brand-text h1{margin:0;font-size:18px;font-weight:700}.brand-text p{margin:2px 0 0;font-size:12px;color:var(--muted)}.role-chip{flex:0 0 auto;font-size:12px;padding:4px 10px;border-radius:999px;font-weight:600}.role-chip.admin{background:var(--primary-soft);color:var(--primary)}.role-chip.student{background:#ffe8c9;color:#b9741a}.role-chip.small{font-size:11px;padding:2px 8px}.header-actions{display:flex;gap:8px;align-items:center}.ghost-btn{border:1px solid var(--border);background:var(--surface);color:var(--text);border-radius:10px;padding:8px 12px;font-size:13px;cursor:pointer;-webkit-tap-highlight-color:transparent}.ghost-btn:active{background:var(--primary-soft)}.ghost-btn.danger{color:#d64545;border-color:#f0caca}.icon-btn-header{padding:8px 10px;min-width:40px}.primary-btn{border:none;background:linear-gradient(135deg,var(--primary),#7c6cf0);color:#fff;border-radius:10px;padding:10px 18px;font-size:15px;font-weight:600;cursor:pointer;box-shadow:0 6px 16px #4f46e547}.primary-btn:disabled{opacity:.6}.main{max-width:720px;margin:0 auto;padding:16px}.login-wrap{display:grid;place-items:center;min-height:100vh;padding:24px}.login-card{width:100%;max-width:380px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:28px 24px;display:flex;flex-direction:column;gap:14px}.login-logo{font-size:40px;text-align:center}.login-card h1{margin:0;text-align:center;font-size:20px}.login-sub{margin:-8px 0 0;text-align:center;color:var(--muted);font-size:13px}.login-card label{display:flex;flex-direction:column;gap:6px;font-size:13px;color:var(--muted)}.login-card input{width:100%;height:46px;padding:0 14px;font-size:16px;border:1px solid var(--border);border-radius:12px;background:var(--surface);outline:none}.login-card input:focus{border-color:var(--primary);box-shadow:0 0 0 3px #4f46e526}.login-error{color:#d64545;font-size:13px;margin:0}.login-card .primary-btn{padding:12px}.search-wrap{position:relative;margin-bottom:16px}.search-icon{position:absolute;left:14px;top:50%;transform:translateY(-50%);width:18px;height:18px;color:var(--muted);pointer-events:none}.search-wrap input{width:100%;height:46px;padding:0 16px 0 42px;font-size:16px;border:1px solid var(--border);border-radius:14px;background:var(--surface);color:var(--text);outline:none;box-shadow:var(--shadow);-moz-appearance:none;appearance:none;-webkit-appearance:none}.search-wrap input:focus{border-color:var(--primary);box-shadow:0 0 0 3px #4f46e526}.filters{display:flex;gap:10px;margin-bottom:16px}.filter{flex:1;display:flex;flex-direction:column;gap:4px;font-size:12px;color:var(--muted)}.filter select{width:100%;height:44px;padding:0 12px;font-size:15px;border:1px solid var(--border);border-radius:12px;background:var(--surface);color:var(--text);outline:none;box-shadow:var(--shadow);-moz-appearance:none;appearance:none;-webkit-appearance:none}.filter select:focus{border-color:var(--primary);box-shadow:0 0 0 3px #4f46e526}.crumbs{display:flex;align-items:center;gap:4px;overflow-x:auto;white-space:nowrap;padding:2px 0 14px;scrollbar-width:none}.crumbs::-webkit-scrollbar{display:none}.crumb{border:none;background:var(--surface);color:var(--muted);font-size:13px;padding:6px 12px;border-radius:999px;cursor:pointer;flex:0 0 auto}.crumb.current{background:var(--primary);color:#fff;font-weight:600}.crumb-sep{color:var(--muted);font-size:14px}.list-heading{font-size:14px;font-weight:600;color:var(--muted);margin:2px 2px 12px}.grid{display:grid;grid-template-columns:1fr;gap:10px}@media (min-width: 480px){.grid{grid-template-columns:1fr 1fr}}.folder-card{display:flex;align-items:center;gap:12px;padding:14px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);cursor:pointer;text-align:left;-webkit-tap-highlight-color:transparent;transition:transform .1s,box-shadow .1s}.folder-card:active{transform:scale(.985)}.folder-icon{font-size:26px;flex:0 0 auto}.folder-label{display:flex;flex-direction:column;gap:3px;min-width:0;flex:1;align-items:flex-start}.folder-name{font-size:16px;font-weight:600;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.count-badge{font-size:11px;color:var(--primary);background:var(--primary-soft);padding:2px 8px;border-radius:999px;font-weight:600}.chevron{font-size:22px;color:#c3c7d6;flex:0 0 auto}.track-list{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:10px}.track-row{display:flex;align-items:center;gap:12px;padding:13px 14px;cursor:pointer;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);-webkit-tap-highlight-color:transparent;transition:transform .1s,box-shadow .1s}.track-row:active{transform:scale(.985);background:var(--primary-soft)}.track-play{width:34px;height:34px;border-radius:50%;display:grid;place-items:center;flex:0 0 auto;color:#fff;font-size:12px;background:linear-gradient(135deg,var(--primary),#7c6cf0);box-shadow:0 4px 10px #4f46e547}.track-meta{min-width:0;flex:1}.track-name{font-size:15px;font-weight:600;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.track-group{font-size:12px;color:var(--muted);margin-top:2px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.empty{text-align:center;padding:60px 20px;color:var(--muted)}.empty-icon{font-size:48px;margin:0 0 14px}.empty p{margin:4px 0}.empty .empty-hint{font-size:13px;color:#a2a8bc}.empty .primary-btn{margin-top:14px}.player{position:fixed;left:0;right:0;bottom:0;z-index:30;background:#fffffff0;-webkit-backdrop-filter:saturate(180%) blur(16px);backdrop-filter:saturate(180%) blur(16px);border-top:1px solid var(--border);box-shadow:0 -8px 30px #1f24301f;padding:10px 16px calc(10px + env(safe-area-inset-bottom))}.player-top{max-width:720px;margin:0 auto;display:flex;align-items:center;gap:10px}.icon-btn{flex:0 0 auto;width:36px;height:36px;border:1px solid var(--border);background:var(--surface);border-radius:12px;color:var(--text);font-size:16px;cursor:pointer;display:grid;place-items:center}.track-title{flex:1;min-width:0;font-size:14px;font-weight:600;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.controls{display:flex;align-items:center;gap:8px;flex:0 0 auto}.ctrl-btn{width:40px;height:40px;border:none;background:transparent;border-radius:50%;color:var(--text);font-size:18px;cursor:pointer;display:grid;place-items:center}.ctrl-btn:active{background:var(--primary-soft)}.play-btn{width:48px;height:48px;border:none;border-radius:50%;color:#fff;font-size:18px;cursor:pointer;display:grid;place-items:center;background:linear-gradient(135deg,var(--primary),#7c6cf0);box-shadow:0 6px 16px #4f46e566}.timeline{max-width:720px;margin:8px auto 0;display:flex;align-items:center;gap:10px}.time{font-size:11px;color:var(--muted);min-width:32px;text-align:center;font-variant-numeric:tabular-nums}.seek{flex:1;height:4px;-moz-appearance:none;appearance:none;-webkit-appearance:none;border-radius:999px;outline:none;cursor:pointer;background:#e0e3ef;accent-color:var(--primary)}.seek::-webkit-slider-thumb{-webkit-appearance:none;width:14px;height:14px;border-radius:50%;background:#fff;border:3px solid var(--primary)}.seek::-moz-range-thumb{width:14px;height:14px;border-radius:50%;background:#fff;border:3px solid var(--primary)}audio{display:none}.admin{display:flex;flex-direction:column;gap:16px}.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:18px}.card h2{margin:0 0 12px;font-size:16px}.form-row{display:flex;flex-wrap:wrap;gap:10px}.form-row input,.form-row select{flex:1;min-width:140px;height:42px;padding:0 12px;font-size:15px;border:1px solid var(--border);border-radius:10px;background:var(--surface);outline:none}.file-input{display:block;width:100%;margin:12px 0;font-size:14px}.unit-input{width:100%;margin-top:10px;height:42px;padding:0 12px;font-size:15px;border:1px solid var(--border);border-radius:10px;outline:none}.unit-input:focus{border-color:var(--primary);box-shadow:0 0 0 3px #4f46e526}.user-list{display:flex;flex-direction:column;gap:8px}.user-row{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:10px 0;border-bottom:1px solid var(--border)}.user-row:last-child{border-bottom:none}.user-meta{display:flex;align-items:center;gap:10px;min-width:0}.user-name{font-weight:600}.user-actions{display:flex;gap:8px}.ok-text{color:#2e7d32;font-size:13px;margin:10px 0 0}.modal-mask{position:fixed;top:0;right:0;bottom:0;left:0;z-index:40;display:grid;place-items:center;padding:24px;background:#1f24306b;-webkit-backdrop-filter:blur(2px);backdrop-filter:blur(2px)}.modal{width:100%;max-width:360px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:0 20px 60px #1f24304d;padding:20px}.modal h3{margin:0 0 12px;font-size:16px}.modal input{width:100%;height:44px;padding:0 12px;font-size:15px;border:1px solid var(--border);border-radius:10px;outline:none}.modal input:focus{border-color:var(--primary);box-shadow:0 0 0 3px #4f46e526}.modal-text{color:var(--muted);font-size:14px;margin:0 0 4px}.modal-actions{display:flex;justify-content:flex-end;gap:10px;margin-top:16px}.primary-btn.danger{background:linear-gradient(135deg,#e5484d,#f0727a);box-shadow:0 6px 16px #e5484d47}