@import"https://fonts.googleapis.com/css2?family=Be+Vietnam+Pro:wght@400;500;600;700&display=swap";:root{color-scheme:light;--ground: #f6f7f9;--surface: #ffffff;--line: #e6e9ef;--line-soft: #eef1f5;--ink: #0f172a;--body: #475569;--muted: #94a3b8;--accent: #2563eb;--accent-hover: #1d4ed8;--accent-wash: #eef4ff;--done: #15803d;--done-wash: #ecfdf3;--warning: #92400e;--warning-wash: #fef3c7;--danger: #b91c1c;--danger-wash: #fee2e2;--radius: 10px;--radius-control: 8px;--font: "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;font-family:var(--font);line-height:1.55;color:var(--ink);background:var(--ground)}*{box-sizing:border-box}html,body,#root{min-height:100%}body{margin:0;min-width:320px;background:var(--ground);color:var(--ink);-webkit-font-smoothing:antialiased}h1,h2,h3{margin:0;line-height:1.25;letter-spacing:-.01em;color:var(--ink)}p,ul{margin:0}a{color:inherit}button,input,textarea{font:inherit}button{transition:background-color .15s ease,border-color .15s ease,color .15s ease}button:focus-visible,input:focus-visible,textarea:focus-visible,a:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.skip-link{position:absolute;left:16px;top:-60px;z-index:30;padding:10px 14px;border-radius:var(--radius-control);background:var(--surface);border:1px solid var(--line)}.skip-link:focus{top:16px}.center-screen{min-height:100vh;display:grid;place-items:center;padding:24px;color:var(--body)}.page-shell{width:min(1120px,100%);margin:0 auto;min-height:100vh;padding:18px 20px 44px}.page-shell-narrow{width:min(760px,100%)}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:0;border-radius:var(--radius-control);padding:11px 16px;font-weight:600;font-size:14.5px;cursor:pointer;text-decoration:none;white-space:nowrap}.btn-primary{background:var(--accent);color:#fff}.btn-primary:hover{background:var(--accent-hover)}.btn-ghost{background:var(--surface);color:var(--body);border:1px solid var(--line)}.btn-ghost:hover{background:var(--ground);color:var(--ink)}.btn-small{padding:8px 12px;font-size:13.5px}.btn:disabled{opacity:.55;cursor:not-allowed}.btn-block{width:100%}.error-banner{padding:12px 14px;border-radius:var(--radius-control);background:var(--danger-wash);color:var(--danger);font-size:14px;font-weight:500}.topbar{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:10px 4px 16px;margin-bottom:26px;border-bottom:1px solid var(--line)}.topbar-lead{display:flex;align-items:center;gap:12px;min-width:0}.topbar-logo{width:30px;height:30px;flex:0 0 auto;object-fit:contain}.topbar-back{display:grid;place-items:center;width:32px;height:32px;flex:0 0 auto;border-radius:var(--radius-control);color:var(--body);text-decoration:none;font-size:19px;line-height:1}.topbar-back:hover{background:var(--ground);color:var(--ink)}.topbar-wordmark{min-width:0;font-weight:600;font-size:14px;color:var(--ink);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.topbar-context{min-width:0;font-weight:600;font-size:15px;color:var(--ink);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.topbar-user{display:flex;align-items:center;gap:10px;flex:0 0 auto;color:var(--body);font-size:14px}.topbar-user-name{font-weight:500}.topbar-avatar{display:grid;place-items:center;width:28px;height:28px;border-radius:50%;background:var(--accent-wash);color:var(--accent);font-weight:700;font-size:12px}.auth-layout{min-height:100vh;display:grid;place-items:center;padding:24px}.auth-card{width:min(400px,100%);background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:34px 30px;display:grid;gap:0}.auth-logo{width:46px;height:46px;object-fit:contain;margin:0 auto 18px}.auth-card h2{text-align:center;font-size:1.35rem;margin:0 0 4px}.auth-sub{text-align:center;color:var(--muted);font-size:12px;font-weight:600;letter-spacing:.04em;margin:0 0 26px}.field{display:grid;gap:6px;margin-bottom:16px}.field label{font-size:13px;font-weight:600;color:var(--body)}.text-input{width:100%;border:1px solid var(--line);border-radius:9px;padding:11px 13px;font-size:14.5px;color:var(--ink);background:var(--surface)}.text-input:hover{border-color:#d3d9e3}.text-input:focus{outline:0;border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-wash)}.auth-card .btn{margin-top:6px}.auth-error{margin-bottom:14px}.auth-switch{text-align:center;color:var(--body);font-size:13.5px;margin:18px 0 0}.auth-switch a{color:var(--accent);text-decoration:none;font-weight:600}.dash-head{display:flex;align-items:baseline;justify-content:space-between;gap:14px;margin-bottom:4px}.dash-head h1{font-size:1.25rem;font-weight:700}.dash-tally{color:var(--muted);font-size:13.5px;font-variant-numeric:tabular-nums}.dash-note{padding:20px 4px;color:var(--body)}.lessons{margin-top:10px}.lesson-row{display:grid;grid-template-columns:30px minmax(0,1fr) auto;gap:16px;align-items:center;padding:18px 8px;border-top:1px solid var(--line);border-radius:var(--radius-control);text-decoration:none;color:inherit}.lessons .lesson-row:last-child{border-bottom:1px solid var(--line)}a.lesson-row:hover{background:var(--ground)}.lesson-idx{display:grid;place-items:center;width:30px;height:30px;border-radius:var(--radius-control);background:var(--ground);color:var(--body);font-weight:700;font-size:14px;font-variant-numeric:tabular-nums}.lesson-info{min-width:0;display:grid;align-content:center}.lesson-title{font-weight:600;font-size:15.5px;color:var(--ink);margin:0 0 2px}.lesson-summary{color:var(--muted);font-size:13.5px;margin:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.lesson-bar{height:5px;border-radius:3px;background:var(--line);margin-top:9px;max-width:240px;overflow:hidden}.lesson-bar>i{display:block;height:100%;border-radius:3px;background:var(--accent)}.lesson-actions{display:flex;align-items:center;gap:14px;justify-content:flex-end}.lesson-state{display:inline-flex;align-items:center;gap:6px;font-size:13px;font-weight:600;white-space:nowrap}.lesson-state-done{color:var(--done)}.lesson-state-locked{color:var(--muted)}.lesson-go{color:var(--accent);font-weight:600;font-size:14px;white-space:nowrap}.lesson-row-locked{cursor:default}.lesson-row-locked .lesson-idx{color:var(--muted)}.lesson-row-locked .lesson-title{color:var(--body)}.icon{width:15px;height:15px;flex:0 0 auto;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round}.dot-done{display:inline-grid;place-items:center;width:18px;height:18px;border-radius:50%;background:var(--done-wash);color:var(--done)}.dot-done .icon{width:11px;height:11px}.lesson-alerts{display:grid;gap:10px;margin-bottom:20px}.lesson-alerts:empty{display:none}.banner{padding:12px 14px;border-radius:var(--radius-control);font-size:14px;font-weight:500}.banner-warning{background:var(--warning-wash);color:var(--warning)}.banner-success{background:var(--done-wash);color:var(--done)}.banner-secondary{background:var(--accent-wash);color:var(--accent-hover)}.lesson-layout{--tutor-width: clamp(340px, 32vw, 400px);display:flex;gap:22px;align-items:start}.lesson-main{flex:1 1 auto;min-width:0;display:grid;gap:4px}.lesson-video{display:block;width:100%;aspect-ratio:16 / 9;border-radius:var(--radius);background:#000}.section-focus{padding:20px 2px 2px}.section-heading-row{display:flex;align-items:flex-start;justify-content:space-between;gap:16px;margin-bottom:6px}.sec-title{font-size:1.1rem;font-weight:700}.sec-goal{color:var(--body);margin:0 0 16px;max-width:64ch}.prog-line{display:flex;align-items:center;gap:12px;color:var(--muted);font-size:13px;margin-bottom:20px;font-variant-numeric:tabular-nums}.prog-line .prog-bar{flex:1;max-width:320px;height:5px;border-radius:3px;background:var(--line);overflow:hidden}.prog-line .prog-bar>i{display:block;height:100%;background:var(--accent)}.seclist{display:grid;gap:2px}.seclist-row{display:grid;grid-template-columns:18px minmax(0,1fr) auto;gap:12px;align-items:center;padding:9px 10px;border-radius:var(--radius-control);font-size:14px}.seclist-row-current{background:var(--accent-wash)}.seclist-mark{display:grid;place-items:center;width:16px;height:16px;border-radius:50%;border:1.5px solid var(--line);color:transparent}.seclist-row-passed .seclist-mark{background:var(--done);border-color:var(--done);color:#fff}.seclist-row-passed .seclist-mark .icon{width:10px;height:10px}.seclist-row-current .seclist-mark{border-color:var(--accent);position:relative}.seclist-row-current .seclist-mark:after{content:"";width:7px;height:7px;border-radius:50%;background:var(--accent)}.seclist-name{min-width:0;color:var(--ink);font-weight:500;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.seclist-row-locked .seclist-name{color:var(--muted);font-weight:400}.seclist-row-current .seclist-name{color:var(--accent);font-weight:600}.seclist-time{color:var(--muted);font-size:12px;font-variant-numeric:tabular-nums}.lesson-blocked{width:min(520px,100%);margin:72px auto 0;padding:32px;display:grid;gap:14px;justify-items:start;background:var(--surface);border:1px solid var(--line);border-radius:14px}.lesson-blocked h1{font-size:1.5rem}.lesson-blocked p{color:var(--body)}.lesson-blocked-tag{font-size:12px;font-weight:700;letter-spacing:.04em;color:var(--muted);text-transform:uppercase}.tutor-panel{display:flex;flex-direction:column;flex:0 0 var(--tutor-width);width:var(--tutor-width);min-width:0;position:sticky;top:16px;align-self:start;height:calc(100vh - 32px);background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden}.tutor-header{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:14px 16px;border-bottom:1px solid var(--line-soft);flex:0 0 auto}.tutor-title{display:flex;align-items:center;gap:8px;font-weight:600;font-size:14px}.tutor-live{width:7px;height:7px;border-radius:50%;background:var(--done)}.tutor-newchat{border:0;background:none;color:var(--muted);font-size:13px;cursor:pointer;padding:4px 6px;border-radius:6px}.tutor-newchat:hover:not(:disabled){color:var(--body);background:var(--ground)}.tutor-newchat:disabled{opacity:.45;cursor:not-allowed}.gate-card{flex:0 0 auto;margin:14px 16px 2px;padding:13px 14px;background:var(--accent-wash);border-radius:9px}.gate-label{font-size:11.5px;font-weight:700;letter-spacing:.04em;color:var(--accent);margin-bottom:5px}.gate-card p{margin:0;font-size:13.5px;line-height:1.5;color:var(--ink)}.chat-list{flex:1;min-height:0;overflow:auto;padding:16px;display:grid;gap:14px;align-content:start;scroll-behavior:smooth}.chat-turn{display:grid;gap:10px}.bubble{max-width:88%;padding:10px 13px;border-radius:14px;font-size:14px;line-height:1.5;white-space:pre-wrap}.bubble-user{justify-self:end;background:var(--accent);color:#fff;border-bottom-right-radius:4px}.bubble-assistant{justify-self:start;background:var(--ground);color:var(--ink);border-bottom-left-radius:4px}.tutor-form{flex:0 0 auto;padding:12px 14px;border-top:1px solid var(--line-soft)}.tutor-input-row{position:relative}.tutor-input-row textarea{width:100%;min-height:58px;max-height:120px;padding:12px 52px 12px 14px;border:1px solid var(--line);border-radius:10px;background:var(--surface);color:var(--ink);line-height:1.4;resize:none}.tutor-input-row textarea:focus{outline:0;border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-wash)}.send-button{position:absolute;right:8px;bottom:8px;display:grid;place-items:center;width:34px;height:34px;border:0;border-radius:var(--radius-control);background:var(--accent);color:#fff;cursor:pointer}.send-button:hover:not(:disabled){background:var(--accent-hover)}.send-button:disabled{opacity:.45;cursor:not-allowed}.send-button .icon{width:17px;height:17px}.tutor-error{margin:0 14px 12px}.unlock-toast{position:fixed;right:24px;bottom:24px;z-index:40;display:flex;align-items:center;gap:10px;max-width:min(360px,calc(100vw - 32px));padding:13px 16px;border-radius:var(--radius);background:var(--surface);border:1px solid var(--line);box-shadow:0 8px 24px #0f172a1f;color:var(--ink);font-size:14px;font-weight:500;animation:toast-in .2s ease-out}.unlock-toast-icon{display:grid;place-items:center;flex:0 0 20px;width:20px;height:20px;border-radius:50%;background:var(--done);color:#fff;font-size:12px}.unlock-toast-content{display:flex;flex-direction:column;gap:4px}.unlock-toast-link{color:var(--accent);font-weight:600;text-decoration:underline}.unlock-toast-link:hover{text-decoration:none}@keyframes toast-in{0%{opacity:0;transform:translateY(8px)}to{opacity:1;transform:translateY(0)}}@media (max-width: 480px){.unlock-toast{right:16px;bottom:16px;left:16px;max-width:none}}@media (max-width: 900px){.lesson-layout{display:grid;grid-template-columns:1fr}.tutor-panel{flex-basis:auto;width:100%;position:static;height:auto;min-height:420px}}@media (max-width: 560px){.page-shell{padding:14px 14px 32px}.topbar-user-name,.lesson-summary{display:none}}@media (prefers-reduced-motion: reduce){*,*:before,*:after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important;scroll-behavior:auto!important}}.stat-row{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:12px;margin-bottom:28px}.stat-tile{display:flex;flex-direction:column;gap:2px;padding:14px 16px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius)}.stat-value{font-size:24px;font-weight:600;color:var(--ink)}.stat-label{font-size:13px;color:var(--muted)}.teacher-block{margin-bottom:32px}.teacher-block h2{font-size:16px;font-weight:600;margin-bottom:12px}.gates{display:flex;flex-direction:column;gap:10px}.gate-row{padding:14px 16px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius)}.gate-head{display:flex;justify-content:space-between;align-items:baseline;gap:12px;margin-bottom:8px}.gate-title{font-weight:500;color:var(--ink)}.gate-rate{font-size:13px;color:var(--body);white-space:nowrap}.gate-bar{display:block;max-width:none;margin-top:0}.gate-meta{display:flex;flex-wrap:wrap;gap:4px 16px;margin-top:8px;font-size:13px;color:var(--muted)}.gate-actions{display:flex;flex-wrap:wrap;gap:8px;margin-top:12px}.gate-summary{margin-top:12px;padding:12px;background:var(--accent-wash);border-radius:var(--radius-control);font-size:14px;color:var(--body);white-space:pre-wrap}.failures{list-style:none;padding:0;margin-top:12px;display:flex;flex-direction:column;gap:10px}.failures li{display:flex;flex-direction:column;gap:2px;padding:10px 12px;background:var(--ground);border-radius:var(--radius-control)}.failure-who{font-size:12px;color:var(--muted)}.failure-answer{font-size:14px;color:var(--ink);white-space:pre-wrap}.failure-note{font-size:13px;color:var(--warning)}.students-wrap{overflow-x:auto}.students{width:100%;border-collapse:collapse;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden}.students th,.students td{padding:10px 14px;text-align:left;font-size:14px;border-bottom:1px solid var(--line-soft)}.students th{font-size:12px;font-weight:500;color:var(--muted);text-transform:uppercase;letter-spacing:.04em}.students tr:last-child td{border-bottom:none}.student-name{display:block;color:var(--ink)}.student-email{display:block;font-size:12px;color:var(--muted)}