:root{--bg:#fff;--ink:#1c1c19;--sub:#77756d;--line:#efece4;--soft:#f7f5f0;--yellow:#f7d64a;--yellow-soft:#fff6cc;--yellow-ink:#65500d;--error:#a23c32;--success:#366a45;--radius:12px;font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;color:var(--ink);background:var(--bg);font-size:14px;line-height:1.65;font-synthesis:none}
*{box-sizing:border-box}body{margin:0}button,input,textarea{font:inherit}button,a,input,textarea{ -webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:not-allowed;opacity:.5}button,a{touch-action:manipulation}a{color:inherit;text-decoration:none}button{background:none;border:0;color:inherit}h1,h2,h3,p{margin:0}h1{font-size:28px;line-height:1.4;font-weight:600;letter-spacing:-.6px}h2{font-size:18px;font-weight:600}h3{font-size:15px;font-weight:600}small{font-size:12px}.muted{color:var(--sub)}.eyebrow{font-size:12px;letter-spacing:.08em;color:var(--sub);margin-bottom:10px}.stack{display:grid;gap:14px}.row{display:flex;align-items:center;gap:12px}.spread{justify-content:space-between}.wrap{flex-wrap:wrap}.grow{flex:1;min-width:0}.spacer{height:30px}.tag{display:inline-flex;align-items:center;padding:2px 8px;border-radius:6px;background:var(--soft);font-size:11px;color:#615f56;white-space:nowrap}.tag.yellow{background:var(--yellow-soft);color:var(--yellow-ink)}.btn{display:inline-flex;align-items:center;justify-content:center;gap:7px;min-height:40px;padding:8px 18px;border:1px solid var(--line);border-radius:999px;white-space:nowrap;font-size:13px;font-weight:500;background:#fff}.btn:hover{background:var(--soft)}.btn.primary{background:var(--yellow);border-color:var(--yellow);color:#3b2f00}.btn.primary:hover{background:#eeca2c}.btn.text{border-color:transparent;background:transparent;padding-left:10px;padding-right:10px}.btn.text:hover{background:var(--soft)}.btn.small{min-height:34px;padding:5px 13px;font-size:12px}.link{color:var(--yellow-ink);text-decoration:underline;text-underline-offset:4px}.icon{width:19px;height:19px;stroke:currentColor;fill:none;stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round;flex:none}.icon-button{display:inline-flex;justify-content:center;align-items:center;width:38px;height:38px;border-radius:9px}.icon-button:hover{background:var(--soft)}:focus-visible{outline:3px solid #c7a42b;outline-offset:4px}input,textarea{width:100%;border:1px solid #dedbd2;border-radius:10px;padding:12px 14px;background:#fff;color:var(--ink)}textarea{resize:vertical;min-height:130px;line-height:1.8}input:focus,textarea:focus{outline:2px solid #eedb8e;outline-offset:1px}label{display:block;font-size:12px;color:var(--sub);margin-bottom:7px}.error{color:var(--error);background:#fff6f4;border:1px solid #edd4d0;padding:12px 16px;border-radius:10px}.success{color:var(--success)}.skip{position:fixed;top:-80px;left:16px;z-index:100;background:var(--yellow);padding:12px}.skip:focus{top:8px}
.shell{display:grid;grid-template-columns:212px minmax(0,1fr);min-height:100vh}.sidebar{border-right:1px solid var(--line);padding:29px 20px;display:flex;flex-direction:column;position:sticky;top:0;height:100dvh}.brand{display:flex;align-items:center;gap:9px;font-family:Georgia,"Times New Roman",serif;font-size:24px;letter-spacing:-.8px}.brandmark{width:22px;height:26px;border:1.5px solid #ae9435;border-radius:4px 10px 10px 4px;position:relative}.brandmark:after{content:"";position:absolute;left:5px;top:5px;bottom:5px;border-left:1px solid #ae9435}.sidebar .subtitle{font-size:11px;color:var(--sub);margin:9px 0 36px 31px}.nav{display:grid;gap:6px}.nav a{display:flex;align-items:center;gap:11px;padding:11px 13px;border-radius:10px;color:#6b6961}.nav a.active{background:var(--soft);color:var(--ink);font-weight:500}.nav a:hover{background:var(--soft)}.nav .number{margin-left:auto;font-size:11px;color:var(--sub)}.sidebar-bottom{margin-top:auto;font-size:11px;color:var(--sub);line-height:1.8;padding:24px 12px 0}.sidebar-bottom .divider{height:1px;background:var(--line);margin-bottom:18px}.topbar{height:70px;border-bottom:1px solid var(--line);padding:0 40px;display:flex;align-items:center;justify-content:space-between;gap:12px;color:var(--sub);font-size:12px}.topbar .save{display:flex;gap:7px;align-items:center}.saved-dot{width:5px;height:5px;border-radius:50%;background:#728475}.avatar{width:29px;height:29px;background:var(--soft);border-radius:50%;display:grid;place-items:center;font-size:12px;color:#5f5d55}.page{max-width:1140px;margin:auto;padding:42px 44px 70px}.page-head{margin-bottom:32px}.page-head p{margin-top:10px;color:var(--sub)}.section-heading{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px;gap:10px}.section-heading .meta{font-size:12px;color:var(--sub)}.intro{padding:26px 0 30px;border-bottom:1px solid var(--line);display:flex;align-items:center;gap:24px}.intro h2{font-size:20px}.intro p{color:var(--sub);margin-top:7px;font-size:13px}.intro-actions{margin-left:auto;flex-shrink:0}.continue{border:1px solid var(--line);border-radius:16px;padding:24px 26px;display:flex;align-items:center;gap:22px;margin:22px 0 38px}.continue.empty{background:#fcfcfa;border-color:transparent}.continue .book-number{font-size:28px;color:#999589;font-family:Georgia,serif}.continue p{margin-top:6px;color:var(--sub);font-size:12px}.progress-track{height:3px;background:var(--line);border-radius:4px;overflow:hidden;margin-top:14px;max-width:300px}.progress-track span{display:block;height:100%;background:#c4a333}.sample-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px}.sample{padding:20px 0 24px;border-top:1px solid var(--line);min-width:0}.sample-no{font-family:Georgia,serif;font-size:24px;color:#b8b3a5;margin-bottom:20px}.sample h3{font-size:16px;margin:10px 0 8px}.sample p{font-size:13px;color:var(--sub);min-height:45px}.sample .footer{margin-top:24px;display:flex;align-items:center;justify-content:space-between}.tiny{font-size:11px;color:var(--sub)}.footnote{font-size:12px;color:var(--sub);border-top:1px solid var(--line);margin-top:30px;padding-top:18px}.empty-state{padding:45px 0}.empty-state h2{font-size:18px}.empty-state p{color:var(--sub);margin:10px 0 20px}.list-row{display:flex;align-items:center;gap:18px;padding:22px 0;border-bottom:1px solid var(--line);min-width:0}.list-row h3{overflow-wrap:anywhere}.list-row p{font-size:12px;color:var(--sub);margin-top:4px}.file-mark{width:43px;height:52px;border:1px solid #e4e0d4;background:#fcfbf7;border-radius:3px 10px 3px 3px;display:grid;place-items:center;color:#82795a;font-size:10px;flex:none}.search{max-width:320px}.search input{border-radius:999px;min-height:40px;padding:8px 16px;font-size:13px}.note-preview{white-space:pre-line;max-height:45px;overflow:hidden;overflow-wrap:anywhere}.note-editor{min-height:390px;border-color:var(--line);font-size:15px}.note-title{border:0;padding:0;font-size:26px;font-weight:600;line-height:1.5;border-radius:0;margin-bottom:24px}.note-source{display:flex;align-items:center;gap:8px;background:var(--soft);padding:12px 16px;border-radius:10px;font-size:12px;margin-bottom:22px}.content-text{white-space:pre-wrap;overflow-wrap:anywhere;font-size:15px;line-height:1.95}.reading{max-width:760px}.reading section{padding:20px 0;border-bottom:1px solid var(--line)}.reading section h3{margin-bottom:10px}.pdf{width:100%;height:65vh;border:1px solid var(--line);border-radius:10px}.reader-toolbar{position:sticky;bottom:16px;margin:25px auto 0;max-width:600px;display:flex;justify-content:center;align-items:center;gap:12px;background:#fff;border:1px solid var(--line);padding:12px;border-radius:999px;box-shadow:0 3px 14px #1c1c1907}
.learn-page{padding:28px 34px 40px;max-width:1420px}.learn-heading{margin-bottom:22px;display:flex;align-items:center;gap:14px}.learn-heading h1{font-size:20px;letter-spacing:-.3px}.learn-heading .grow p{font-size:12px;color:var(--sub);margin-top:4px}.learn-layout{display:grid;grid-template-columns:185px minmax(0,1fr);gap:28px}.outline-title{font-size:11px;color:var(--sub);margin:4px 0 17px;letter-spacing:.1em}.outline{display:grid;gap:5px;align-content:start}.step{display:flex;align-items:flex-start;gap:10px;text-align:left;padding:10px 9px;border-radius:8px;color:var(--sub);font-size:12px;width:100%}.step:hover{background:var(--soft)}.step.current{color:var(--ink);background:var(--yellow-soft)}.step-num{font-family:Georgia,serif;min-width:15px}.study-area{min-width:0}.study-title{display:flex;gap:12px;align-items:center;margin:2px 0 18px}.study-title h2{font-size:19px}.study-count{font-size:11px;color:var(--sub);white-space:nowrap}.board{min-height:310px;background:#fcfcfa;border:1px solid var(--line);border-radius:14px;padding:27px 30px;position:relative;display:flex;flex-direction:column}.board-meta{display:flex;align-items:center;justify-content:space-between;font-size:10px;color:#817f74;letter-spacing:.07em;margin-bottom:25px}.board h3{font-size:17px;font-weight:500;text-align:center;margin-bottom:24px}.board-content{display:flex;flex:1;align-items:center;justify-content:center;gap:12px;flex-wrap:wrap;min-height:130px}.board-card{border:1px solid #dedbd0;border-radius:10px;padding:20px 18px;background:white;flex:1;min-width:110px;max-width:330px;text-align:center;font-size:15px;line-height:1.7;white-space:pre-line}.board-card:first-child{border-top:3px solid #d4b544}.board.equation .board-content{flex-direction:column;gap:7px}.board.equation .board-card{border:0;background:transparent;max-width:100%;width:100%;font-family:ui-monospace,"SFMono-Regular",Menlo,monospace;font-size:18px;padding:8px 4px;flex:none}.board.tree .board-content{position:relative;gap:16px;padding-top:14px}.board.tree .board-card{position:relative}.board.tree .board-card:before{content:"";position:absolute;top:-14px;left:50%;height:13px;border-left:1px solid #d2cdbf}.board.tree .board-card:after{content:"";position:absolute;top:-15px;left:0;width:100%;border-top:1px solid #d2cdbf}.board .reveal-placeholder{color:var(--sub);font-size:13px}.board-controls{display:flex;justify-content:space-between;align-items:center;margin-top:20px;font-size:11px;color:var(--sub)}.talk{margin:24px 0;padding-left:17px;border-left:2px solid #e1cc75}.talk-label{font-size:11px;color:var(--sub);margin-bottom:7px}.talk p{font-size:15px;line-height:1.95;white-space:pre-line}.reflection{font-size:13px;color:#626057;margin-top:14px}.study-actions{display:flex;justify-content:space-between;border-top:1px solid var(--line);padding-top:18px;gap:10px}.study-actions .utilities{display:flex;gap:5px}.source-button{font-size:11px;color:var(--sub);text-decoration:underline;text-underline-offset:3px}.exercise{max-width:680px;margin:30px auto;padding:28px 0}.exercise h2{margin:12px 0 22px;font-size:23px}.option{display:flex;align-items:flex-start;gap:12px;border:1px solid #e5e1d7;border-radius:12px;padding:15px;margin-bottom:12px;cursor:pointer;font-size:14px;color:var(--ink)}.option input{width:17px;min-width:17px;height:17px;margin:3px 0 0;accent-color:#b3962d}.option:has(input:checked){background:#fffaf0;border-color:#ceba70}.feedback{padding:18px 20px;border-radius:10px;background:var(--soft);margin:20px 0;font-size:14px}.feedback p{margin-top:7px}.completed{max-width:650px;margin:35px auto;padding:20px 0}.completed h1{margin:15px 0}.completed p{color:var(--sub);margin-bottom:25px}.completion-list{margin:24px 0;border-top:1px solid var(--line)}.completion-list div{padding:12px 0;border-bottom:1px solid var(--line);display:flex;justify-content:space-between;font-size:13px}.answer-state{color:#797257;font-size:11px}.hint{background:#fcfaf2;padding:14px 17px;border-radius:10px;margin:15px 0;font-size:13px}.sample-question{display:block;width:100%;border:1px solid var(--line);border-radius:9px;padding:11px 13px;text-align:left;font-size:13px;margin:8px 0}.sample-question:hover{background:var(--soft)}.chat{max-height:280px;overflow-y:auto;margin:18px 0;display:grid;gap:15px}.chat-item{padding:13px 16px;border-radius:10px;white-space:pre-wrap;font-size:13px;background:var(--soft)}.chat-item.user{background:#fff9e6;margin-left:30px}.chat-item .tiny{display:block;margin-bottom:5px}.inline-source{display:inline-flex;margin-top:8px;color:var(--yellow-ink);text-decoration:underline;font-size:11px}
dialog{width:min(620px,calc(100vw - 32px));max-height:88dvh;overflow:auto;border:1px solid var(--line);border-radius:18px;padding:28px;box-shadow:0 15px 60px #1c1c1914;color:var(--ink);background:#fff}dialog::backdrop{background:#1c1c1940}dialog .dialog-head{display:flex;align-items:center;justify-content:space-between;gap:15px;margin-bottom:20px}dialog h2{font-size:19px}dialog p.description{font-size:13px;color:var(--sub);margin-bottom:20px}dialog .source-section{border-top:1px solid var(--line);padding:16px 0}dialog .source-section h3{font-size:13px;margin-bottom:7px}dialog .source-section p{font-size:14px;white-space:pre-wrap}.upload{border:1px dashed #d4cfc1;padding:26px 18px;border-radius:12px;text-align:center;margin:20px 0}.upload input{display:none}.upload.dragover{background:var(--yellow-soft)}.upload p{font-size:12px;color:var(--sub);margin-top:10px}.dialog-divider{border-top:1px solid var(--line);padding-top:20px;margin-top:22px}.modal-samples{display:grid;gap:10px}.modal-samples button{padding:14px 0;border-bottom:1px solid var(--line);text-align:left;display:flex;align-items:center;gap:14px;width:100%}.modal-samples button:hover{color:var(--yellow-ink)}.dialog-footer{display:flex;align-items:center;justify-content:flex-end;gap:10px;margin-top:18px}.loading{padding:70px;color:var(--sub)}#toast{position:fixed;bottom:26px;left:50%;transform:translateX(-50%);background:#262621;color:white;border-radius:999px;padding:11px 22px;font-size:12px;z-index:100;opacity:0;pointer-events:none;transition:opacity .15s;max-width:90vw;text-align:center}#toast.visible{opacity:1}.mobile-brand{display:none}.fail-banner{margin:16px 40px}.start-over{font-size:11px;color:var(--sub)}
@media(min-width:1600px){.board{min-height:370px}}@media(max-width:1100px){.shell{grid-template-columns:184px minmax(0,1fr)}.sidebar{padding:26px 14px}.page{padding:32px 28px 50px}.learn-page{padding:24px}.learn-layout{grid-template-columns:154px minmax(0,1fr);gap:18px}.sample-grid{gap:18px}.board{padding:22px}.study-actions{flex-wrap:wrap}.intro{align-items:flex-start}.intro-actions{margin-top:4px}}@media(max-width:767px){:root{font-size:14px}.shell{display:block}.sidebar{height:auto;position:static;border-right:0;border-bottom:1px solid var(--line);padding:17px 16px 0}.brand{font-size:23px}.sidebar .subtitle,.sidebar-bottom{display:none}.nav{display:flex;gap:17px;margin-top:20px}.nav a{border-radius:0;padding:8px 0 12px;font-size:13px;gap:6px;border-bottom:2px solid transparent}.nav a .icon{display:none}.nav a.active{background:none;border-bottom-color:#d6b735}.topbar{height:45px;padding:0 16px;font-size:10px}.topbar .avatar{display:none}.topbar .row{gap:6px}.page{padding:28px 18px 40px}h1{font-size:25px}.page-head{margin-bottom:24px}.intro{display:block;padding-top:10px}.intro-actions{margin-top:20px}.continue{padding:20px 16px;gap:14px;flex-wrap:wrap;margin-bottom:30px}.continue .book-number{font-size:24px}.continue .btn{margin-left:auto}.sample-grid{grid-template-columns:1fr;gap:0}.sample{display:grid;grid-template-columns:34px 1fr;column-gap:14px;padding:20px 0}.sample-no{grid-row:1/4;margin:0}.sample .tag{justify-self:start}.sample h3{margin:6px 0}.sample p{grid-column:2;min-height:0}.sample .footer{grid-column:2;margin-top:13px}.list-row{gap:12px;flex-wrap:wrap}.list-row>.btn{margin-left:55px}.search{max-width:none;width:100%}.file-mark{width:35px;height:45px}.list-row .grow{min-width:calc(100% - 65px)}.note-title{font-size:22px}.note-editor{font-size:16px;min-height:45vh}.note-source{align-items:flex-start}.learn-page{padding:20px 16px 35px}.learn-heading{align-items:flex-start;flex-wrap:wrap}.learn-heading h1{font-size:18px}.learn-heading .back-label{display:none}.learn-layout{display:block}.outline{display:flex;overflow-x:auto;gap:7px;margin-bottom:20px;padding-bottom:8px}.outline-title{display:none}.step{min-width:100px;width:auto;max-width:150px;align-items:center;border:1px solid var(--line);padding:9px 10px}.step span:last-child{overflow:hidden;white-space:nowrap;text-overflow:ellipsis}.study-title{margin-bottom:14px}.study-title h2{font-size:18px}.board{padding:18px 14px;min-height:275px}.board-meta{font-size:9px;margin-bottom:20px}.board h3{font-size:16px}.board-card{font-size:14px;padding:14px 12px;min-width:95px}.board.equation .board-card{font-size:15px;overflow-wrap:anywhere}.board-controls{gap:10px}.talk p{font-size:15px}.study-actions{gap:13px}.study-actions>.row{width:100%;justify-content:space-between;order:2}.study-actions .utilities{width:100%;justify-content:space-between}.exercise{margin:15px 0;padding-top:15px}.exercise h2{font-size:20px}.completed{margin:15px 0}.section-heading{flex-wrap:wrap}.pdf{height:58vh}.reader-toolbar{border-radius:14px;flex-wrap:wrap;bottom:10px}.reader-toolbar .tiny{width:100%;text-align:center}dialog{padding:20px;max-height:90dvh}input,textarea{font-size:16px}.fail-banner{margin:12px 16px}.upload{padding:22px 12px}.btn{min-height:42px}.btn.small{min-height:38px}.icon-button{width:40px;height:40px}}
@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}
.pdf-controls{margin:0 0 15px}.pdf-pages{background:#f5f5f2;min-height:250px;border:1px solid var(--line);padding:16px;border-radius:10px;text-align:center}.pdf-pages canvas{display:block;width:auto;height:auto;max-width:100%;margin:auto;background:#fff;box-shadow:0 1px 6px #1c1c190d}.pdf-pages .error{text-align:left}.pdf-pages>p{padding:60px 10px}
.generated-section{margin:12px 0 35px;padding:4px 0 28px;border-bottom:1px solid var(--line)}.generated-section>.muted{font-size:13px}.generated-section .list-row:last-child{border-bottom:0}#prepare-result .error,#generate-result .error{margin:16px 0}
.board-card{overflow-wrap:anywhere}.source-button{overflow-wrap:anywhere;max-width:65%;text-align:right}

/* Lemon Learn 完整站首页；保留既有资料、学习与笔记布局。 */
.home-status{display:flex;align-items:flex-start;gap:12px;padding:15px 18px;border:1px solid var(--line);background:#fcfbf7;border-radius:12px;margin-bottom:32px}.home-status p{font-size:12px;line-height:1.8;color:var(--sub)}.home-status .tag{flex:none;margin-top:1px}.home-entries{margin-bottom:10px}.entry-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.entry-card{display:flex;flex-direction:column;align-items:flex-start;width:100%;min-width:0;min-height:185px;padding:20px;border:1px solid var(--line);border-radius:13px;background:var(--bg);text-align:left;color:var(--ink)}.entry-card:hover{background:#fcfbf7;border-color:#dfd7be}.entry-icon{display:grid;place-items:center;width:32px;height:32px;margin-bottom:13px;background:var(--yellow-soft);color:var(--yellow-ink);border-radius:8px}.entry-title{display:block;font-size:16px;font-weight:600;margin-bottom:6px}.entry-description{display:block;font-size:12px;line-height:1.8;color:var(--sub);overflow-wrap:anywhere}.entry-action{display:block;margin-top:auto;padding-top:15px;font-size:12px;color:var(--yellow-ink)}.home-continue-heading{margin-top:32px}.sample-intro{font-size:13px;color:var(--sub);line-height:1.8;margin-bottom:20px}.sample .footer{gap:8px;flex-wrap:wrap}.sidebar .brand{font-size:23px;white-space:nowrap}.sidebar .brandmark{flex:none}@media(max-width:1100px){.sidebar .brand{font-size:20px;gap:7px}.sidebar .brandmark{width:19px}.entry-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}@media(max-width:767px){.sidebar .brand{font-size:23px}.nav{overflow-x:auto;gap:18px;overscroll-behavior-inline:contain}.nav a{white-space:nowrap;flex:none}.home-status{padding:13px 14px;gap:10px;flex-wrap:wrap;margin-bottom:26px}.entry-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.entry-card{padding:16px;min-height:190px}.entry-title{font-size:15px}.home-entries .section-heading .meta{font-size:11px}.home-continue-heading{margin-top:28px}}@media(max-width:420px){.entry-grid{grid-template-columns:1fr}.entry-card{min-height:0}.entry-action{padding-top:13px}.sample .footer{gap:8px}}