:root{--ink:#17333a;--muted:#677a7d;--line:#dce7e5;--paper:#f5f9f8;--card:#fff;--accent:#087d78;--accent-dark:#086762;--danger:#ad3f38;--shadow:0 12px 35px rgba(17,57,61,.07)}
*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.65 system-ui,-apple-system,"Microsoft YaHei",sans-serif}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}.shell{width:min(1180px,calc(100% - 40px));margin:auto}.site-header{background:#fff;border-bottom:1px solid var(--line)}.header-inner{min-height:68px;display:flex;align-items:center;gap:28px}.brand{font-size:20px;font-weight:800;color:var(--ink);white-space:nowrap}.brand span{font-size:13px;color:var(--accent);margin-left:7px}.header-inner nav{display:flex;gap:19px;flex-wrap:wrap}.header-inner nav a{color:var(--ink);font-size:14px}.account{margin-left:auto;display:flex;align-items:center;gap:12px;font-size:13px;color:var(--muted);white-space:nowrap}.account form{margin:0}.main-content{min-height:calc(100vh - 142px);padding:32px 0 72px}.site-footer{border-top:1px solid var(--line);padding:18px 0;color:var(--muted);font-size:12px}.card{background:var(--card);border:1px solid var(--line);border-radius:15px;padding:24px;box-shadow:var(--shadow)}h1,h2,h3,p{margin-top:0}h1{font-size:clamp(28px,3.5vw,42px);line-height:1.22;letter-spacing:-.02em}h2{font-size:22px;line-height:1.35}h3{font-size:17px}.eyebrow{color:var(--accent);font-size:12px;font-weight:800;letter-spacing:.1em;text-transform:uppercase}.muted{color:var(--muted)}.page-heading{margin:10px 0 28px}.page-heading>p:last-child{color:var(--muted)}.page-heading>a{display:inline-block;margin-bottom:16px}.hero{background:linear-gradient(115deg,#073f49,#087c76);border-radius:19px;color:#fff;padding:48px;display:grid;grid-template-columns:1fr 180px;gap:30px;margin-bottom:38px;box-shadow:var(--shadow)}.hero h1{max-width:680px}.hero p{color:#d9f1ee}.hero .eyebrow{color:#a5e7dd}.hero-stat{display:grid;align-content:center;gap:2px;text-align:center;border-left:1px solid rgba(255,255,255,.3)}.hero-stat strong{font-size:36px;line-height:1.2}.hero-stat span{font-size:12px;margin-bottom:13px;color:#cbe5e2}.actions,.form-actions{display:flex;align-items:center;gap:12px;flex-wrap:wrap}.button{display:inline-flex;align-items:center;justify-content:center;border-radius:9px;padding:10px 17px;border:1px solid transparent;font:inherit;font-size:14px;font-weight:700;cursor:pointer;text-decoration:none}.button:hover{text-decoration:none}.button.primary{color:#fff;background:var(--accent)}.button.primary:hover{background:var(--accent-dark)}.button.secondary{background:#e9f4f2;color:var(--accent-dark);border-color:#c9e5e0}.button.danger{background:#fff4f2;color:var(--danger);border-color:#ecc8c2}.hero .button.primary{background:#fff;color:#075d59}.hero .button.secondary{background:transparent;color:#fff;border-color:#a9d2ce}.link-button{border:0;padding:0;background:none;color:var(--accent);font:inherit;cursor:pointer}.danger-text{color:var(--danger)}.section-heading{display:flex;justify-content:space-between;align-items:baseline;margin:30px 0 14px}.section-heading h2{margin:0}.chapter-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}.chapter{display:flex;flex-direction:column;min-height:138px;color:var(--ink);position:relative}.chapter>span:first-child{font-size:12px;color:var(--accent);font-weight:800}.chapter strong{font-size:19px;margin-top:12px}.chapter .arrow{position:absolute;right:22px;top:20px;color:var(--accent)}.list-card{padding:6px 18px}.list-row{display:flex;align-items:center;gap:16px;border-bottom:1px solid var(--line);padding:17px 4px;color:var(--ink)}.list-row:last-child{border-bottom:0}.list-row>strong{flex:1}.list-row>span:last-child{color:var(--accent);white-space:nowrap}.list-row .path{color:var(--muted);font-size:12px;max-width:40%;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.pill{display:inline-block;background:#edf5f3;color:#16776f;border-radius:999px;padding:3px 9px;font-size:11px;font-weight:700;white-space:nowrap}.pill.approved{background:#e7f6e9;color:#278051}.empty{color:var(--muted)}.auth-card{width:min(440px,100%);margin:7vh auto}.stack{display:grid;gap:17px}.stack label,.filter-row label{display:grid;gap:6px;font-weight:650;font-size:14px}input,textarea,select{width:100%;padding:11px 12px;border-radius:8px;border:1px solid #cbdad8;background:#fff;color:var(--ink);font:inherit;font-size:14px}input:focus,textarea:focus,select:focus{outline:2px solid #94d2ca;border-color:var(--accent)}textarea{resize:vertical}input[type=checkbox],input[type=radio]{width:auto}.auth-card .button{width:100%}.ask-form{display:grid;gap:12px}.ask-form label{font-weight:700}.form-actions{justify-content:flex-end}.answer-card{margin-top:24px}.answer-text{white-space:pre-wrap;line-height:1.9}.tags{display:flex;gap:8px;flex-wrap:wrap}.tag{padding:6px 12px;background:#e5f3f1;border-radius:999px}.source-list{display:grid;gap:12px}.source-head{display:flex;justify-content:space-between;gap:14px}.source p{color:var(--muted);white-space:pre-wrap;margin:12px 0 0}.two-column{display:grid;grid-template-columns:1fr 1fr;gap:16px}.facts{display:grid;grid-template-columns:110px 1fr;gap:10px}.facts dt{color:var(--muted)}.facts dd{margin:0}.relation{display:flex;align-items:center;gap:10px;padding:9px 0;border-bottom:1px solid var(--line)}.relation:last-child{border:0}.edit-panel{margin-top:20px}.edit-panel form:last-child{margin-top:20px}.narrow{width:min(700px,100%)}.filter-row{display:flex;align-items:end;gap:14px;flex-wrap:wrap;margin-bottom:18px}.filter-row label{min-width:170px;flex:1}.notice{padding:13px 16px;border-radius:9px;margin-bottom:18px;background:#e5f5ec;color:#216045}.notice.error{background:#fff0ed;color:#983c36}.exam-question{margin-bottom:14px}.exam-question h2{font-size:19px}.options{display:grid;gap:8px}.options label{display:flex;align-items:center;gap:11px;padding:10px;border:1px solid var(--line);border-radius:8px;cursor:pointer}.exam-question textarea{margin-top:10px}.good{color:#218050}.bad{color:#ad3f38}.review-form{display:flex;gap:9px;margin-top:15px}.review-form select{width:130px}.review-form input{flex:1}.admin-grid{grid-template-columns:1fr 1fr;align-items:start;margin-top:18px}.admin-list{max-height:900px;overflow:auto}.admin-item{border-bottom:1px solid var(--line);padding:12px 0;display:grid;gap:7px}.admin-item:last-child{border:0}.admin-item .actions{font-size:13px}.two-fields{display:grid;grid-template-columns:1fr 1fr;gap:12px}.check-row{cursor:pointer}.check-row input{width:auto}.publish-row{display:flex;justify-content:space-between;align-items:center;margin-top:18px}.publish-row input{width:auto}.table-wrap{overflow:auto}table{width:100%;border-collapse:collapse}th,td{text-align:left;padding:12px;border-bottom:1px solid var(--line);font-size:13px}th{color:var(--muted)}.review-text{font-family:Consolas,"Microsoft YaHei",monospace;line-height:1.6}
@media(max-width:850px){.header-inner{flex-wrap:wrap;padding:12px 0;gap:8px}.header-inner nav{order:3;width:100%;overflow:auto;white-space:nowrap;flex-wrap:nowrap}.hero{grid-template-columns:1fr;padding:30px}.hero-stat{grid-template-columns:repeat(4,1fr);border-left:0;border-top:1px solid rgba(255,255,255,.3);padding-top:14px}.hero-stat strong{font-size:26px}.hero-stat span{margin:0}.chapter-grid{grid-template-columns:repeat(2,1fr)}.two-column{grid-template-columns:1fr}.list-row{flex-wrap:wrap}.list-row .path{max-width:100%}}@media(max-width:560px){.shell{width:min(100% - 24px,1180px)}.chapter-grid{grid-template-columns:1fr}.card{padding:17px}.hero-stat{display:none}.review-form,.source-head{flex-wrap:wrap}.two-fields{grid-template-columns:1fr}}
.inline-citation{font-weight:800;background:#e6f4f1;border-radius:4px;padding:0 3px}.page-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(88px,1fr));gap:8px}.page-tile{display:grid;gap:2px;padding:10px;background:#fff;border:1px solid var(--line);border-radius:8px}.page-tile span{font-size:11px;color:var(--muted)}.page-tile.reviewed{border-color:#6ec6a5;background:#effaf3}
.network-card{margin-bottom:16px}.network-card svg{width:100%;height:auto;max-height:330px;background:#f8fbfa;border-radius:12px}.network-edge{stroke:#a9c9c3;stroke-width:2}.network-node circle{fill:#d7eeea;stroke:#75b9ad;stroke-width:1}.network-node:hover circle{fill:#b4e0d7}.network-node text{fill:#194c4a;font-size:12px;pointer-events:none}.network-center circle{fill:#087d78}.network-center text{fill:#fff;font-weight:800;font-size:15px}.network-note{fill:#677a7d;font-size:12px}
.graph-chapters{display:grid;gap:14px}.graph-chapter{padding:0;overflow:hidden}.graph-chapter summary{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap;padding:18px 22px;cursor:pointer;list-style-position:inside}.graph-chapter summary strong{font-size:18px}.graph-counts{color:var(--muted);font-size:13px}.graph-tree-level{list-style:none;margin:0;padding:0 18px 8px 30px}.graph-tree-level .graph-tree-level{margin-left:12px;padding:0 0 0 21px;border-left:2px solid var(--line)}.graph-tree-item{margin:0}.graph-tree-row{display:flex;align-items:center;gap:10px;min-height:41px;padding:5px 0;flex-wrap:wrap}.graph-tree-row>a{font-weight:650;color:var(--ink)}.graph-tree-row>a:hover{color:var(--accent)}.graph-source,.graph-child-count{font-size:12px;color:var(--muted)}.graph-child-count{margin-left:auto}.graph-tree-item:target>.graph-tree-row{background:#e6f4f1;border-radius:7px}.graph-tree-item .pill{min-width:38px;text-align:center}@media(max-width:560px){.graph-chapter summary{padding:15px}.graph-tree-level{padding-left:15px}.graph-tree-level .graph-tree-level{margin-left:5px;padding-left:10px}.graph-child-count{margin-left:0}}
.network-scroll{overflow-x:auto}.network-scroll svg{min-width:760px;max-height:none}.network-scroll svg.full-network{min-width:900px}.network-node rect{fill:#d7eeea;stroke:#75b9ad;stroke-width:1.5}.network-node:hover rect{fill:#b4e0d7}.network-node .network-label{fill:#194c4a;font-size:14px;font-weight:700}.network-node .network-meta{fill:#567a77;font-size:11px}.network-center rect{fill:#087d78}.network-center .network-label,.network-center .network-meta{fill:#fff}.network-section-label{fill:#677a7d;font-size:14px;font-weight:700}.graph-children{margin-bottom:16px}.graph-child-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:9px}.graph-child-link{display:flex;align-items:center;gap:9px;flex-wrap:wrap;padding:10px 12px;border:1px solid var(--line);border-radius:9px;color:var(--ink)}.graph-child-link:hover{border-color:#75b9ad;background:#f4fbf9;text-decoration:none}.graph-child-link strong{flex:1}.graph-child-link small{color:var(--muted);white-space:nowrap}

/* Chapter canvas and compact teaching workflows. */
.graph-workspace{margin:18px 0 30px}.graph-toolbar{display:flex;align-items:end;gap:10px;flex-wrap:wrap;margin-bottom:12px;padding:14px 18px}.graph-toolbar>label:first-child{display:grid;gap:5px;flex:1;min-width:250px;font-size:13px;font-weight:700}.graph-toggle{display:inline-flex!important;align-items:center;gap:7px;font-size:13px;font-weight:650;white-space:nowrap}.graph-toggle input{width:auto}.graph-layout{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:12px;align-items:stretch}.graph-stage{padding:10px;min-width:0;background:#f9fcfb}.graph-canvas{height:650px;min-width:0;border-radius:12px;background:radial-gradient(circle at 20% 15%,#f0f9f7,#fff 65%)}.graph-status{font-size:12px;margin:8px 12px 2px}.graph-legend{display:flex;gap:15px;margin:0 12px 4px;color:#5d7575;font-size:12px}.graph-legend span:nth-child(2){color:#bd7752}.graph-legend span:nth-child(3){color:#797eb0}.graph-sidebar{max-height:720px;overflow:auto;padding:20px}.graph-sidebar h2{font-size:20px;overflow-wrap:anywhere}.graph-sidebar .facts{grid-template-columns:92px minmax(0,1fr)}.graph-sidebar .facts dd{overflow-wrap:anywhere}.graph-matches{max-height:230px;overflow:auto;margin-bottom:8px}.graph-match{display:block;width:100%;text-align:left;padding:9px 10px;background:#eef7f5;border:0;border-radius:8px;margin-bottom:5px;color:var(--ink);font:inherit;font-size:13px;cursor:pointer}.graph-match:hover{background:#d8eee9}.graph-inspector .actions{margin-top:15px}.graph-inspector .button{font-size:12px;padding:7px 10px}.graph-chapter-filter{align-items:center}.graph-chapter-filter .graph-toggle{padding-top:18px}
.graph-level-counts{margin:0 0 10px;padding:0 4px;font-size:13px}
.graph-page-heading{margin:0 0 14px}.graph-page-heading h1{font-size:34px;margin-bottom:6px}.graph-page-heading>p:last-child{margin-bottom:0;font-size:14px}.graph-chapter-filter{padding:12px 16px;margin-bottom:10px}.graph-chapter-filter label{min-width:155px}.graph-chapter-filter input,.graph-chapter-filter select{padding:8px 10px}.graph-chapter-filter .graph-toggle{padding-top:14px}.graph-workspace{margin-top:10px}.graph-workspace .graph-toolbar{padding:10px 14px}.graph-workspace .graph-toolbar input{padding:8px 10px}
.teacher-question-layout{display:grid;gap:16px;margin-top:18px}.teacher-question-new summary{cursor:pointer;font-size:18px;font-weight:700}.teacher-question-new form{margin-top:16px;max-width:720px}
.card-create{margin:14px 0}.card-list{display:grid;gap:10px;margin-top:14px}.knowledge-card-edit{padding:16px 20px}.knowledge-card-edit summary{display:flex;gap:12px;align-items:center;cursor:pointer}.knowledge-card-edit summary strong{flex:1}.knowledge-card-edit>p{margin:14px 0 5px}.knowledge-card-edit form{border-top:1px solid var(--line);padding-top:12px;margin-top:12px;max-width:760px}
.paper-builder{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(310px,1fr);gap:16px;align-items:start}.paper-builder>section,.paper-builder>aside{min-width:0}.paper-filters{display:grid;grid-template-columns:1fr 1fr 1.5fr;gap:9px}.paper-filters label{display:grid;gap:5px;font-size:13px;font-weight:650}.paper-question-row{display:flex;align-items:center;gap:10px;padding:12px 0;border-bottom:1px solid var(--line)}.paper-question-row>div:first-child{flex:1;min-width:0}.paper-question-row small{display:block;color:var(--muted);font-size:11px}.paper-question-row strong{display:block;font-size:13px;line-height:1.45;overflow-wrap:anywhere}.paper-question-row .actions{gap:4px}.paper-question-row .button{padding:5px 8px;font-size:11px;white-space:nowrap}.paper-candidates{min-height:150px}.paper-pages{justify-content:center;margin-top:12px}.paper-selection{position:sticky;top:18px;max-height:calc(100vh - 34px);overflow:auto}.paper-selection h2{margin-bottom:5px}.paper-selection>form{border-top:1px solid var(--line);padding-top:12px;margin-top:14px}.paper-selection #paper-save{display:grid;gap:11px}.paper-selection #paper-save .button{width:100%}
.ask-controls{display:flex;align-items:end;gap:18px}.ask-controls label{display:grid;gap:5px;min-width:230px}.ask-controls p{font-size:12px;margin:0 0 10px}.answer-text{white-space:normal}.answer-text p:last-child{margin-bottom:0}.answer-text h2,.answer-text h3{font-size:19px}.answer-text code{background:#eef5f4;padding:1px 4px;border-radius:3px}.source details{margin-top:8px}.source summary{cursor:pointer;color:var(--accent);font-size:13px}.source-full{white-space:pre-wrap;max-height:360px;overflow:auto;font-size:13px}.table-wrap td:first-child{min-width:140px}.table-wrap td:nth-child(2){min-width:220px}.admin-grid{grid-template-columns:minmax(300px,.8fr) minmax(0,1.2fr)}.admin-list{max-height:none}
.answer-text .display-math{max-width:100%;overflow-x:auto;margin:1rem 0}.answer-text .math-fallback{white-space:pre-wrap;font-family:Consolas,"Microsoft YaHei",monospace}
@media(max-width:1100px){.graph-layout{grid-template-columns:minmax(0,1fr) 260px}.paper-builder{grid-template-columns:1fr}.paper-selection{position:static;max-height:none}}
@media(max-width:850px){.graph-layout{grid-template-columns:1fr}.graph-canvas{height:520px}.graph-sidebar{max-height:none}.paper-filters{grid-template-columns:1fr 1fr}.paper-filters label:last-child{grid-column:1/-1}}
.question-review-history{margin-top:18px}.question-review-history details{border-top:1px solid var(--line);padding:12px 0}.question-review-history summary{cursor:pointer;font-weight:700}.question-review-history pre{white-space:pre-wrap;overflow-wrap:anywhere;max-height:320px;overflow:auto;background:#f8fbfa;border:1px solid var(--line);border-radius:8px;padding:12px;font-size:12px}
.ask-new-form { margin: 0 0 16px; }
.ask-suggestions{display:grid;gap:8px}
.ask-suggestions>span{color:var(--muted);font-size:13px}
.ask-suggestion-list{display:flex;flex-wrap:wrap;gap:8px}
.ask-suggestion{padding:7px 12px;border:1px solid #c9e5e0;border-radius:999px;background:#f3faf8;color:var(--accent-dark);font:inherit;font-size:13px;text-align:left;cursor:pointer}
.ask-suggestion:hover{background:#e0f2ee}
.ask-suggestion:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.ask-history { margin-bottom: 16px; }
.ask-history h2 { margin-top: 0; }
.ask-history-turn { padding: 12px 0; border-top: 1px solid #e4ebeb; }
.ask-history-turn p { margin: 6px 0 0; color: #526578; white-space: pre-wrap; }
.ask-progress{display:flex;align-items:flex-start;gap:14px;margin-top:4px;padding:16px 18px;border:1px solid #b9dad4;border-radius:11px;background:#eef8f6}
.ask-progress[hidden]{display:none}
.ask-result[hidden]{display:none}
.ask-progress-body{min-width:0;flex:1}
.ask-progress-title{display:block;color:#075f59;font-size:15px}
.ask-progress-question{margin:5px 0;color:var(--ink);overflow-wrap:anywhere;white-space:pre-wrap}
.ask-progress-detail{margin:0;color:var(--muted);font-size:13px}
.ask-spinner{width:20px;height:20px;flex:none;margin-top:3px;border:3px solid #b8ddd6;border-top-color:var(--accent);border-radius:50%;animation:ask-spin .8s linear infinite}
.ask-progress.is-error{border-color:#ecc8c2;background:#fff4f2}
.ask-progress.is-error .ask-progress-title{color:var(--danger)}
.ask-progress.is-error .ask-spinner{display:none}
.ask-form :disabled,.ask-new-form :disabled{cursor:not-allowed;opacity:.62}
@keyframes ask-spin{to{transform:rotate(360deg)}}
@media(prefers-reduced-motion:reduce){.ask-spinner{animation:none;border-color:var(--accent)}}
.course-formula-image{display:block;max-width:100%;height:auto;background:white;margin:12px 0}
.formula-content{padding:16px 0;border-bottom:1px solid var(--border,#dde5eb)}
.course-content p,.graph-node-note p{white-space:pre-wrap;overflow-wrap:anywhere}
.course-content .katex-display,.graph-node-note .katex-display{overflow-x:auto;overflow-y:hidden;padding:8px 0}
.held-pages .list-row > strong,.held-pages .list-row > span:last-child{flex-shrink:0;white-space:nowrap}
.held-pages .list-row > span:nth-child(2){min-width:0;overflow-wrap:anywhere}
.question-richtext{overflow-wrap:anywhere;line-height:1.65}.question-richtext>:last-child{margin-bottom:0}.question-richtext table{display:block;overflow-x:auto;max-width:100%;margin:12px 0}.question-richtext th,.question-richtext td{border:1px solid var(--line);padding:5px 9px;white-space:nowrap}.question-richtext .katex-display{overflow-x:auto;overflow-y:hidden;padding:4px 0}.question-asset{margin:12px 0}.question-asset img{display:block;max-width:100%;height:auto;border:1px solid var(--line);border-radius:7px;background:#fff}.question-asset figcaption{font-size:12px;color:var(--muted);margin-top:5px}