:root{font-family:Segoe UI,Nirmala UI,system-ui,sans-serif;color:#17352b;background:#f5f9f6;font-synthesis:none;--bg:#f5f9f6;--surface:#fff;--soft:#e7f3ed;--line:#dce7e0;--ink:#17352b;--muted:#647c70;--accent:#207b56;--reading-size:18px;--reading-leading:1.8;--reading-font:"Segoe UI",system-ui,sans-serif}*{box-sizing:border-box}body{margin:0;color:var(--ink);background:var(--bg)}button,input,textarea,select{font:inherit}button,a,input,select,textarea{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:default;opacity:.55}a{color:var(--accent);text-decoration:none}button{border:1px solid var(--line);background:var(--surface);border-radius:12px;padding:10px 14px;color:inherit;font-weight:650}button:hover,a:hover{filter:brightness(.96)}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid #87c8a9;outline-offset:3px}header{position:sticky;top:0;z-index:20;background:var(--soft);border-bottom:1px solid var(--line);min-height:78px;padding:14px max(18px,calc((100vw - 1150px)/2));display:flex;align-items:center;justify-content:space-between;gap:12px;padding-top:max(14px,env(safe-area-inset-top))}.brand{display:flex;align-items:center;gap:12px;min-width:0}.brand-icon{display:grid;place-items:center;background:var(--accent);color:#fff;border-radius:16px;font-size:29px;font-weight:700;width:44px;height:48px;flex-shrink:0}.brand small{display:block;font-size:10px;letter-spacing:.2em;color:var(--accent);font-weight:800;margin-bottom:4px}.brand strong{display:block;font-size:16px;max-width:65vw;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.head-actions{display:flex;gap:7px}.head-actions button{padding:8px 10px;border-color:transparent;background:#ffffff80}main{max-width:1150px;margin:0 auto;padding:30px 24px 115px}.eyebrow{font-size:11px;letter-spacing:.17em;font-weight:800;color:var(--accent)}h1{font-size:clamp(28px,4vw,42px);line-height:1.18;letter-spacing:-.035em;margin:12px 0 14px;font-weight:800}h2{font-size:23px;letter-spacing:-.02em}h3{line-height:1.4;font-size:18px;margin:10px 0}p{line-height:1.65}.muted,small{color:var(--muted)}.library-intro{max-width:650px;margin-bottom:28px}.search{display:flex;align-items:center;border:1px solid var(--line);background:var(--surface);border-radius:16px;padding:0 15px;margin-top:22px}.search span{font-size:27px;color:var(--muted)}.search input{border:0;background:none;padding:16px 12px;width:100%;outline:0;color:inherit}.folder-grid{display:grid;grid-template-columns:repeat(7,minmax(0,1fr));gap:10px;margin:20px 0 32px}.folder{padding:16px 12px;text-align:left;display:flex;flex-direction:column;gap:9px;min-height:135px;border-radius:18px;align-items:flex-start}.folder-icon{background:var(--soft);width:34px;height:34px;border-radius:10px;display:grid;place-items:center;font-size:21px;color:var(--accent)}.folder strong{font-size:12px}.folder small{font-size:10px;font-weight:400}.folder.active{background:var(--soft);border-color:var(--accent)}.folder.active .folder-icon{background:var(--accent);color:#fff}.section-title{display:flex;align-items:center;gap:16px;margin:20px 0}.section-title h2{margin:0}.section-title>span{margin-left:auto;color:var(--muted);font-size:13px}.topic-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.topic-card{border:1px solid var(--line);border-radius:20px;background:var(--surface);padding:22px;display:flex;flex-direction:column;min-width:0}.topic-card>small{text-transform:uppercase;letter-spacing:.07em;font-size:9px}.topic-card>p{font-size:13px;color:var(--muted);margin:0 0 22px;display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden}.topic-actions{margin-top:auto;display:flex;justify-content:space-between;gap:8px;align-items:center;font-size:12px}.count-button{background:var(--soft);color:var(--accent);font-size:11px;border:0;padding:8px}.notes-link{font-weight:750}.count-row{display:flex;gap:6px;border-top:1px solid var(--line);margin-top:16px;padding-top:13px}.count-row button{font-size:10px;padding:6px 8px;background:transparent;border:0;border-radius:6px}.bottom-nav{position:fixed;bottom:0;left:50%;transform:translate(-50%);width:min(650px,100%);border:1px solid var(--line);border-bottom:0;border-radius:22px 22px 0 0;background:var(--surface);z-index:30;display:flex;justify-content:space-around;padding:10px 8px max(12px,env(safe-area-inset-bottom));box-shadow:0 -8px 40px #133b2310}.bottom-nav a,.bottom-nav button{border:0;border-radius:12px;display:flex;flex-direction:column;align-items:center;gap:3px;padding:8px 22px;color:var(--muted);font-size:20px;background:transparent}.bottom-nav span{font-size:10px;font-weight:650}.bottom-nav .selected{background:var(--soft);color:var(--accent)}dialog{background:var(--surface);color:var(--ink);border:1px solid var(--line);border-radius:24px;width:min(560px,calc(100vw - 24px));max-height:85dvh;padding:28px;box-shadow:0 20px 70px #0002}dialog::backdrop{background:#17352b66;backdrop-filter:blur(4px)}.dialog-close{position:absolute;top:10px;right:10px;border:0;background:transparent;font-size:23px}.primary{display:inline-block;background:var(--accent);color:#fff;border:0;border-radius:13px;padding:14px 20px;text-align:center;font-weight:750}.secondary{display:block;background:var(--soft);border:0;padding:14px 20px;width:100%;margin-top:10px}.stack{display:flex;flex-direction:column;gap:10px}.stack .secondary{margin:0}label{display:block;font-size:13px;font-weight:700;margin:18px 0}input:not([type=range]),select,textarea{display:block;width:100%;border:1px solid var(--line);background:var(--bg);color:var(--ink);border-radius:10px;padding:12px;margin:8px 0}input[type=range]{width:100%;accent-color:var(--accent)}label output{float:right}.info-card{background:var(--soft);border-radius:14px;padding:18px;margin:16px 0}.info-card p{font-size:13px}.outside,.welcome{max-width:620px;margin:10vh auto;padding:32px;text-align:center}.outside .brand-icon{margin:auto}.outside small,.welcome small{display:block;font-size:12px;margin-top:22px}.outside p,.welcome p{color:var(--muted)}.big-icon{font-size:80px;color:var(--accent)}.opening{padding:30vh 20px;text-align:center;font-size:26px;font-weight:800}.opening small{font-size:14px;font-weight:400}#toast{position:fixed;bottom:105px;left:50%;transform:translate(-50%);background:#183e2f;color:#fff;border-radius:12px;padding:12px 20px;z-index:100;max-width:90vw;box-shadow:0 8px 30px #0002;opacity:0;pointer-events:none;transition:opacity .15s;font-size:13px}#toast.show{opacity:1}.reader-toolbar,.quiz-toolbar{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin-bottom:20px}.reader-toolbar button{font-size:12px}.reader{max-width:830px;margin:0 auto;background:var(--surface);border:1px solid var(--line);border-radius:20px;padding:34px;font:var(--reading-size)/var(--reading-leading) var(--reading-font)}.reader .lesson-block{margin-bottom:18px;scroll-margin-top:100px;content-visibility:auto;contain-intrinsic-size:auto 80px}.reader h1{font-size:1.8em}.reader h2{border-top:1px solid var(--line);padding-top:22px;font-size:1.5em}.reader h3{font-size:1.2em}.reader h4{font-size:1.05em}.reader p{line-height:inherit}.reader strong{font-weight:800}.reader table{border-collapse:collapse;max-width:100%;display:block;overflow:auto;font-size:.9em}.reader th,.reader td{border:1px solid var(--line);padding:10px;text-align:left;min-width:95px}.reader th{background:var(--soft)}.reader blockquote{border-left:3px solid var(--accent);padding:8px 18px;background:var(--soft);margin:14px 0}.reader img,.reader svg,.reader canvas{max-width:100%;height:auto}.reader figure{margin:12px 0}.reader figcaption{font-size:.8em;color:var(--muted)}.reader pre,.source-editor{font:12px/1.6 Consolas,monospace;white-space:pre-wrap;overflow-wrap:anywhere}.reader pre{background:var(--bg);padding:14px;border-radius:10px}.reader .node-note,.reader .node-example{border-left:3px solid var(--accent);background:var(--soft);padding:16px;border-radius:0 12px 12px 0}.callout-label{font-size:.8em;color:var(--accent);font-weight:800;text-transform:uppercase;letter-spacing:.07em}.callout-warning,.callout-important{border-left-width:5px!important}.figure-title{font-size:.85em;font-weight:750;margin:10px 0}.chart-frame{position:relative;height:280px}.graph-legend{display:flex;gap:8px;flex-wrap:wrap}.graph-legend button{font-size:11px}.graph-legend span{display:inline-block;width:10px;height:3px;margin-right:5px}.graph-readout{font-size:12px}.function-graph text{font-size:10px;fill:var(--muted)}.contents-list{display:flex;flex-direction:column;gap:6px}.contents-list button{text-align:left;font-size:13px}.load-more{font-size:12px;color:var(--muted);text-align:center;padding:20px}.katex-display{overflow-x:auto;overflow-y:hidden;padding:5px 0}.katex{font-size:1.1em}.math-error,.render-failure{color:#a83c32}.quiz-toolbar select{width:auto;margin:0 0 0 auto}.quiz-toolbar,.quiz-toolbar button{font-size:12px}.quiz-sheet{max-width:850px;margin:auto;border:1px solid var(--line);border-radius:22px;padding:28px;background:var(--surface);overflow-anchor:none}.question-text{font-size:var(--reading-size);font-weight:750;line-height:1.65;min-height:90px}.question-text p{margin:0 0 16px}.quiz-sheet #diagram svg{max-width:100%;max-height:260px;height:auto}.options{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:20px 0}.options>button{display:flex;gap:12px;text-align:left;align-items:center;min-height:60px;padding:13px 16px;font-size:16px}.options b{background:var(--soft);border-radius:8px;padding:7px 10px;font-size:12px}.options p{margin:0}.options button:disabled{opacity:1}.options .correct{border-color:#258858;background:#edf8f0}.options .wrong{border-color:#c76b62;background:#fff0ed}.feedback-slot{height:clamp(185px,29dvh,320px);overflow-y:auto;overscroll-behavior:contain;border-top:1px solid var(--line);padding-top:16px;scrollbar-gutter:stable;overflow-anchor:none;font-size:15px;line-height:1.7}.feedback-placeholder{color:var(--muted);font-size:13px;padding:35px 8px;text-align:center}.feedback strong{display:block;font-size:13px}.feedback.correct>strong{color:#258858}.feedback.incorrect>strong{color:#a14b41}.quiz-navigation{display:flex;align-items:center;justify-content:space-between;gap:8px;max-width:850px;margin:18px auto}.quiz-navigation span{font-size:11px;color:var(--muted);text-align:center}.quiz-navigation button{font-size:13px}.admin-tabs{display:flex;gap:8px;overflow-x:auto;padding-bottom:15px}.admin-tabs button{white-space:nowrap;font-size:12px}.admin-tabs .selected{background:var(--accent);color:#fff}.order-row{display:flex;align-items:center;gap:8px;padding:10px 0;border-bottom:1px solid var(--line)}.order-row strong{flex:1;font-size:13px}.order-row>span{font-size:11px;color:var(--muted);min-width:20px}.order-row button{font-size:12px;padding:7px 10px}.source-editor{min-height:330px;width:100%;font-family:Consolas,monospace;resize:vertical}.student{display:flex;justify-content:space-between;gap:15px;border:1px solid var(--line);padding:18px;border-radius:14px;margin-bottom:12px;background:var(--surface);overflow-wrap:anywhere}.student h3{margin:0}.student p{font-size:13px;margin:7px 0}.student small{font-size:11px}.student-actions{display:flex;gap:5px;flex-wrap:wrap;align-items:center}.student-actions button{font-size:11px}#save-order{margin-top:20px}pre{white-space:pre-wrap;word-break:break-word}html[data-theme=paper]{--bg:#f6f1e7;--surface:#fffdf8;--soft:#eee6d5;--line:#e1d8c5;--ink:#383327;--muted:#80755f;--accent:#716039}html[data-theme=dark]{--bg:#141e1a;--surface:#1d2b24;--soft:#293f32;--line:#354d40;--ink:#e2ede6;--muted:#a1b6a9;--accent:#5caf83}html[data-theme=dark] .options .correct{background:#254732}html[data-theme=dark] .options .wrong{background:#4b302e}@media(max-width:1000px){.folder-grid{grid-template-columns:repeat(4,minmax(0,1fr))}.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}@media(max-width:600px){header{padding-left:15px;padding-right:15px;min-height:72px}.brand strong{max-width:48vw;font-size:13px}.brand-icon{width:36px;height:40px;border-radius:12px;font-size:23px}.head-actions{gap:3px}.head-actions button{padding:7px}main{padding:22px 15px 110px}.library-intro h1{font-size:31px}.folder-grid{grid-template-columns:repeat(3,minmax(0,1fr));gap:8px}.folder{min-height:117px;padding:12px 10px;border-radius:15px}.folder strong{font-size:11px}.folder small{font-size:9px}.topic-grid{grid-template-columns:1fr}.topic-card{padding:20px}.bottom-nav a,.bottom-nav button{padding:7px 18px}.reader{padding:20px 17px;border-radius:15px}.reader-toolbar{gap:6px}.reader-toolbar button{font-size:10px;padding:9px}.quiz-sheet{padding:19px 15px}.question-text{font-size:18px;min-height:85px}.options{gap:8px;grid-template-columns:1fr}.options>button{min-height:49px;padding:9px 12px;font-size:15px}.options b{padding:5px 9px}.options{margin:13px 0}.feedback-slot{height:190px;font-size:14px}.quiz-toolbar{gap:5px}.quiz-toolbar select,.quiz-toolbar button{font-size:11px;padding:8px}.student{flex-direction:column}.order-row{gap:5px}.order-row button{padding:7px}.order-row strong{font-size:12px}.outside{margin-top:7vh}.reader .lesson-block{contain-intrinsic-size:auto 140px}}@media print{html,body{display:none!important}}.quiz-toolbar #quiz-status{margin-left:auto}.share-question{display:grid;place-items:center;width:38px;height:38px;flex:0 0 38px;border:1px solid var(--line,#d3e5db);border-radius:50%;background:transparent;color:inherit;padding:8px}.share-question svg{width:21px;height:21px}.support-chat{width:min(850px,100%);margin:auto}.message-log{display:flex;flex-direction:column;gap:12px;padding:12px 0 22px}.chat-message{max-width:86%;border:1px solid var(--line);border-radius:18px 18px 18px 5px;padding:13px 16px;background:var(--surface);align-self:flex-start;overflow-wrap:anywhere}.chat-message.mine{background:var(--soft);align-self:flex-end;border-radius:18px 18px 5px}.chat-message strong{font-size:11px;color:var(--accent)}.chat-message p{white-space:pre-wrap;margin:7px 0;font-size:15px;line-height:1.6}.chat-message small{font-size:10px;color:var(--muted)}#message-form{background:var(--surface);border:1px solid var(--line);padding:16px;border-radius:18px}#message-body{min-height:95px;resize:vertical}.message-send{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-top:10px}.message-send small{font-size:11px;color:var(--muted)}.inbox-row{width:100%;display:flex;align-items:center;justify-content:space-between;text-align:left;padding:16px;border:1px solid var(--line);border-radius:15px;margin:10px 0;background:var(--surface)}.inbox-row span{min-width:0}.inbox-row strong,.inbox-row small{display:block}.inbox-row small{font-size:11px;color:var(--muted);margin:5px 0}.inbox-row p{margin:5px 0 0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;max-width:70vw}.unread-count{border-radius:20px;background:var(--accent);color:#fff;min-width:25px;padding:5px;text-align:center;font-size:11px}.page-controls{display:flex;gap:10px;justify-content:space-between;margin:18px 0}.admin-tabs{overflow-x:auto;white-space:nowrap}#share-question-text{width:100%;min-height:180px;font-size:13px;resize:vertical}.liquid-dock .dock-item{flex-shrink:0}@media(max-width:600px){.liquid-dock .dock-item{padding:8px 7px;min-width:37px}.liquid-dock .dock-label{font-size:9px}.liquid-dock .dock-icon svg{width:21px;height:21px}.liquid-dock{gap:0}.chat-message{max-width:93%}}