:root{--font: "Segoe UI", system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;--radius: 12px;--accent: #3b6ef5;--surface: #ffffff;--border: rgba(0, 0, 0, .12);--muted: #6b7180}*{box-sizing:border-box}html,body,#root{margin:0;height:100%}body{font-family:var(--font);-webkit-font-smoothing:antialiased}.app{display:flex;flex-direction:column;height:100dvh;transition:background .3s ease,color .3s ease}.muted{opacity:.62}.topbar{flex:0 0 auto;min-height:56px;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:8px 16px;border-bottom:1px solid var(--border)}.brand{display:flex;align-items:center;gap:9px;font-weight:650;font-size:16px}.brand-mark{font-size:20px}.topbar-actions{display:flex;align-items:center;gap:8px}.control-btn{-webkit-appearance:none;-moz-appearance:none;appearance:none;border:1px solid var(--border);background:transparent;color:inherit;border-radius:10px;height:40px;min-width:40px;padding:0 12px;font-size:14px;font-family:var(--font);cursor:pointer;display:inline-flex;align-items:center;justify-content:center;gap:6px;transition:background .15s ease,transform .05s ease}.control-btn:hover{background:#7f7f7f1f}.control-btn:active{transform:scale(.97)}.control-btn:disabled{opacity:.45;cursor:not-allowed}.control-btn.primary{background:var(--accent);border-color:var(--accent);color:#fff}.select{-webkit-appearance:none;-moz-appearance:none;appearance:none;border:1px solid var(--border);background:transparent;color:inherit;border-radius:10px;height:40px;padding:0 12px;font-size:14px;font-family:var(--font);cursor:pointer;max-width:46vw}.popover{position:relative}.popover-panel{position:absolute;top:calc(100% + 8px);right:0;z-index:30;min-width:220px;max-width:80vw;max-height:70vh;overflow-y:auto;padding:6px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:0 12px 32px #0000002e}.menu-label{font-size:11px;text-transform:uppercase;letter-spacing:.06em;opacity:.55;padding:8px 10px 4px}.menu-item{display:block;width:100%;text-align:left;border:none;background:transparent;color:inherit;border-radius:8px;padding:9px 10px;font-size:14px;font-family:var(--font);cursor:pointer}.menu-item:hover{background:#7f7f7f1f}.menu-sep{height:1px;background:var(--border);margin:6px 4px}.composer{flex:0 0 auto;padding:12px 16px;border-bottom:1px solid var(--border);display:flex;justify-content:center}.create{width:100%;max-width:820px}.create-row{display:flex;flex-wrap:wrap;gap:8px;align-items:center}.create-input{flex:1 1 240px;min-width:0;height:40px;border:1px solid var(--border);background:var(--surface);color:inherit;border-radius:10px;padding:0 14px;font-size:14px;font-family:var(--font)}.create-input:focus{outline:2px solid var(--accent);outline-offset:-1px}.create-split{height:40px;font-size:13px}.create-btn,.create-upload,.create-toggle{white-space:nowrap}.create-text{width:100%;margin-top:8px;border:1px solid var(--border);background:var(--surface);color:inherit;border-radius:10px;padding:10px 12px;font-size:13px;font-family:var(--font);resize:vertical}.create-error{margin-top:8px;font-size:13px;color:#d9534f}.create-info{margin-top:8px;font-size:13px}.notice{flex:0 0 auto;padding:8px 16px;font-size:13px;background:#fdf0e3;color:#8a5a1a;text-align:center}.lessons-strip{flex:0 0 auto;display:flex;gap:8px;overflow-x:auto;padding:10px 16px;border-bottom:1px solid var(--border);-webkit-overflow-scrolling:touch}.lesson-tab{flex:0 0 auto;max-width:220px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;border:1px solid var(--border);background:transparent;color:inherit;border-radius:999px;padding:7px 14px;font-size:13px;font-family:var(--font);cursor:pointer}.lesson-tab:hover{background:#7f7f7f1a}.lesson-tab.active{background:var(--accent);border-color:var(--accent);color:#fff}.stage{flex:1 1 auto;min-height:0;display:flex;justify-content:center}.whiteboard-scroll{width:100%;max-width:880px;height:100%;overflow-y:auto;overflow-x:hidden;scroll-behavior:smooth;box-shadow:0 0 0 1px var(--border)}.whiteboard-svg{display:block}.footer{flex:0 0 auto;padding:10px 16px 14px;border-top:1px solid var(--border);display:flex;flex-direction:column;gap:10px}.lesson-meta{font-size:14px}.controls{display:flex;align-items:center;flex-wrap:wrap;gap:10px}.time{font-variant-numeric:tabular-nums;font-size:13px;opacity:.75;min-width:38px;text-align:center}.scrubber{flex:1 1 160px;min-width:90px;accent-color:var(--accent);cursor:pointer}.rate{-webkit-appearance:none;-moz-appearance:none;appearance:none;border:1px solid var(--border);background:transparent;color:inherit;border-radius:10px;height:40px;padding:0 10px;font-size:14px;font-family:var(--font);cursor:pointer}.modal-overlay{position:fixed;top:0;right:0;bottom:0;left:0;z-index:50;background:#00000073;display:flex;align-items:center;justify-content:center;padding:16px}.modal{width:100%;max-width:380px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:0 18px 48px #0000004d;padding:22px}.modal-title{margin:0 0 4px;font-size:20px;font-weight:650}.modal-sub{margin:0 0 16px;font-size:13px;line-height:1.5}.modal-field{width:100%;margin-bottom:10px}.modal-submit{width:100%;margin-top:4px}.attest{display:flex;gap:8px;align-items:flex-start;font-size:12px;line-height:1.45;margin:4px 0 12px;color:var(--muted);cursor:pointer}.attest input{margin-top:3px;flex:0 0 auto}.modal-switch{display:block;width:100%;margin-top:14px;border:none;background:transparent;color:var(--accent);font-size:13px;font-family:var(--font);cursor:pointer}.paywall{width:100%;max-width:880px;height:100%;display:flex;align-items:center;justify-content:center;padding:24px}.paywall-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:32px 28px;text-align:center;max-width:360px;width:100%}.paywall-lock{font-size:40px}.paywall-title{margin:12px 0 2px;font-size:22px;font-weight:650}.paywall-price{font-size:34px;font-weight:700;margin:16px 0}.paywall-buy{width:100%}.menu-danger{color:#d9534f}.legal-modal{max-width:560px}.legal-updated{margin:0 0 12px;font-size:12px}.legal-body{max-height:60vh;overflow-y:auto;font-size:14px;line-height:1.55;padding-right:4px}.legal-body p{margin:0 0 10px}.legal-heading{font-size:15px;font-weight:650;margin:18px 0 6px}.legal-links{display:flex;flex-wrap:wrap;align-items:center;gap:8px;font-size:12px}.legal-link{border:none;background:transparent;color:var(--accent);font-size:inherit;font-family:var(--font);cursor:pointer;padding:0;text-decoration:underline}.consent-bar{position:fixed;left:50%;bottom:16px;transform:translate(-50%);z-index:45;width:min(640px,94vw);display:flex;align-items:center;gap:12px;padding:12px 16px;font-size:13px;line-height:1.4;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:0 12px 32px #00000038}.consent-ok{flex:0 0 auto;height:36px}.video-progress{position:fixed;left:50%;bottom:96px;transform:translate(-50%);z-index:40;width:min(420px,90vw);padding:12px 16px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:0 12px 32px #00000038}.video-progress-label{font-size:13px;margin-bottom:8px;font-variant-numeric:tabular-nums}.video-progress-bar{height:6px;border-radius:999px;background:#7f7f7f33;overflow:hidden}.video-progress-fill{height:100%;background:var(--accent);border-radius:999px;transition:width .2s ease}@media (max-width: 640px){.brand-name{display:none}.whiteboard-scroll{box-shadow:none}.control-btn,.create-input,.create-split,.rate{height:44px}.lesson-tab{max-width:150px}}