:root{--bg: #eef3f6;--surface: #ffffff;--side: #f8fafc;--line: #d6dde7;--line-soft: #e2e8f0;--text: #1f2937;--muted: #64748b;--brand: #176b87;--brand-dark: #0f4c5c;--brand-soft: #eaf7fb;--success: #287d5b;font-family:Microsoft YaHei,PingFang SC,Arial,sans-serif}*{box-sizing:border-box}body{margin:0;min-height:100vh;background:var(--bg);color:var(--text)}button,textarea,input{font:inherit}button{cursor:pointer}.login-page{min-height:100vh;display:grid;place-items:center;background:var(--bg)}.login-panel{width:360px;background:#fff;border:1px solid var(--line);border-radius:8px;padding:34px;text-align:center;box-shadow:0 20px 50px #0f172a14}.login-mark,.brand-mark{background:var(--brand);color:#fff;display:grid;place-items:center}.login-mark{width:52px;height:52px;border-radius:8px;margin:0 auto 16px;font-size:24px}.login-panel h1{margin:0 0 8px;font-size:24px}.login-panel p{margin:0 0 24px;color:var(--muted)}.login-form{display:grid;gap:12px;text-align:left}.login-form label{display:grid;gap:6px;color:var(--text);font-size:13px;font-weight:700}.login-form input{width:100%;border:1px solid #cbd5e1;border-radius:6px;padding:10px 12px;outline:none}.login-form input:focus{border-color:var(--brand)}.primary-btn,.send-btn{border:0;background:var(--brand);color:#fff;border-radius:6px;font-weight:700}.primary-btn{width:100%;padding:12px}.primary-btn:disabled{opacity:.6}.error{margin-top:12px;color:#b91c1c;font-size:13px}.login-notice{margin-top:12px;color:var(--muted);font-size:13px;line-height:1.6}.text-btn{border:0;background:transparent;color:var(--brand);padding:4px;font-size:12px;text-align:center}.app-shell{height:100vh;min-height:760px;display:grid;grid-template-rows:56px 1fr}.topbar{background:var(--surface);border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 20px}.brand{display:flex;align-items:center;gap:10px;font-weight:700;color:var(--brand-dark);font-size:17px}.brand-mark{width:30px;height:30px;border-radius:6px}.logout-btn{border:1px solid var(--line);background:#fff;color:var(--muted);border-radius:6px;padding:6px 14px;font-size:13px}.logout-btn:hover{border-color:var(--brand);color:var(--brand)}.workspace{min-height:0;display:grid;grid-template-columns:260px minmax(520px,1fr) 380px}.sessions,.sources{background:var(--side);min-height:0}.sessions{border-right:1px solid var(--line)}.sources{border-left:1px solid var(--line);display:grid;grid-template-rows:52px 210px 1fr}.pane-head{height:52px;display:flex;align-items:center;justify-content:space-between;padding:0 14px;border-bottom:1px solid var(--line)}.pane-title{color:var(--muted);font-size:13px;font-weight:700}.icon-btn{width:30px;height:30px;border:1px solid var(--line);border-radius:6px;background:#fff;color:var(--brand-dark)}.icon-btn:hover{border-color:var(--brand);color:var(--brand)}.session-list,.source-list{padding:12px;overflow:auto}.session,.source-card{width:100%;text-align:left;border:1px solid var(--line-soft);background:#fff;border-radius:7px;padding:10px;margin-bottom:9px;color:var(--text)}.session{display:grid;grid-template-columns:1fr 28px;align-items:center;gap:8px}.session.active,.source-card.active{border-color:var(--brand);background:var(--brand-soft)}.session-main{min-width:0}.session-title,.source-name{display:block;font-size:13px;font-weight:700}.session-meta,.source-chapter,.source-top{display:block;color:var(--muted);font-size:12px;margin-top:4px}.session-delete{width:26px;height:26px;border:1px solid transparent;border-radius:6px;background:transparent;color:var(--muted);line-height:1}.session-delete:hover,.session-delete:focus{border-color:#fecaca;background:#fff1f2;color:#b91c1c}.chat{background:var(--surface);display:grid;grid-template-rows:52px 1fr auto;min-width:0}.chat-head{border-bottom:1px solid var(--line);display:flex;align-items:center;padding:0 18px}.chat-title{font-size:15px;font-weight:700}.chat-sub{color:var(--muted);font-size:12px;margin-top:2px}.message-list{overflow:auto;padding:22px 24px;display:flex;flex-direction:column;gap:14px;background:#fbfcfe}.message{max-width:84%;border-radius:8px;padding:12px 14px;font-size:14px;line-height:1.7}.message.user{align-self:flex-end;background:#e8f4f8;border:1px solid #c8e1e8}.message.ai{align-self:flex-start;background:#fff;border:1px solid var(--line-soft);box-shadow:0 6px 18px #0f172a0a}.assistant-content{color:var(--text);line-height:1.75;overflow-x:auto}.assistant-content>*:first-child{margin-top:0}.assistant-content>*:last-child{margin-bottom:0}.assistant-content p{margin:0 0 10px}.assistant-content h1,.assistant-content h2,.assistant-content h3{margin:16px 0 8px;line-height:1.35;color:#102a43}.assistant-content h1{font-size:18px}.assistant-content h2{font-size:16px}.assistant-content h3{font-size:15px}.assistant-content ul,.assistant-content ol{margin:8px 0 12px;padding-left:22px}.assistant-content li{margin:4px 0}.assistant-content blockquote{margin:10px 0;padding:8px 12px;border-left:3px solid var(--brand);background:#f4f9fb;color:#334155}.assistant-content code{background:#f1f5f9;border:1px solid #e2e8f0;border-radius:4px;padding:1px 4px;font-family:Consolas,Courier New,monospace;font-size:.92em}.assistant-content pre{overflow:auto;background:#0f172a;color:#e2e8f0;border-radius:6px;padding:12px}.assistant-content table{width:max-content;max-width:none;min-width:min(720px,100%);border-collapse:collapse;margin:12px 0 14px;font-size:13px;line-height:1.45;background:#fff}.assistant-content th,.assistant-content td{border:1px solid #cbd5e1;padding:9px 11px;vertical-align:top;min-width:96px;max-width:340px;text-align:left;white-space:normal;word-break:break-word;overflow-wrap:anywhere}.assistant-content th{background:#eef4f8;color:#0f172a;font-weight:700;text-align:center}.assistant-content td:first-child,.assistant-content th:first-child{min-width:118px;max-width:190px;font-weight:700}.assistant-content td:not(:first-child){text-align:left}.assistant-content tr:nth-child(2n) td{background:#fbfdff}.assistant-content sup{font-size:.72em;line-height:0;vertical-align:super}.assistant-content sup a{color:var(--brand);font-weight:700;text-decoration:none}.assistant-content sup a:hover{text-decoration:underline}.assistant-content .math-display{display:block;width:max-content;max-width:100%;margin:10px auto;overflow-x:auto;color:#111827;font-family:"Cambria Math",Cambria,Times New Roman,serif;font-size:20px;line-height:1.35;white-space:nowrap}.assistant-content .math-inline{display:inline-flex;align-items:center;font-family:"Cambria Math",Cambria,Times New Roman,serif}.assistant-content .math-frac{display:inline-flex;flex-direction:column;align-items:center;justify-content:center;vertical-align:middle;margin:0 3px;line-height:1.15}.assistant-content .math-num{display:block;min-width:100%;padding:0 6px 2px;text-align:center;border-bottom:1.5px solid currentColor}.assistant-content .math-den{display:block;min-width:100%;padding:2px 6px 0;text-align:center}.assistant-content .math-op{padding:0 4px}.assistant-content .math-tag{display:inline-block;margin-left:18px;font-size:.75em}.assistant-content .citation-list{margin-top:16px;padding-top:12px;border-top:1px solid var(--line-soft)}.assistant-content .citation-list li{margin-bottom:6px;font-size:13px}.assistant-content .citation-list a{color:var(--brand)}.inline-cite{border:0;background:transparent;color:var(--brand);font-weight:700;padding:0 2px}.input-area{border-top:1px solid var(--line);padding:14px 18px;background:#fff;display:grid;grid-template-columns:1fr 88px;gap:10px}.composer-input{resize:none;border:1px solid #cbd5e1;border-radius:8px;padding:10px 12px;min-height:58px;outline:none}.composer-input:focus{border-color:var(--brand)}.send-btn{min-height:58px}.send-btn:disabled{opacity:.5}.preview{padding:12px;overflow:auto}.preview-meta{display:flex;justify-content:space-between;margin-bottom:10px;color:var(--muted);font-size:12px}.page-preview{height:300px;border:1px solid #cbd5e1;border-radius:6px;background:#fff;padding:18px;display:flex;flex-direction:column;gap:12px;overflow:auto}.preview-page-image{width:100%;height:auto;border:1px solid var(--line-soft);border-radius:4px}.preview-note{color:var(--muted);font-size:12px;line-height:1.6}.preview-actions{display:flex;gap:8px;margin-top:12px}.secondary-btn{border:1px solid #cbd5e1;background:#fff;color:var(--brand-dark);border-radius:6px;padding:8px 10px;font-weight:700;font-size:12px;text-decoration:none}.secondary-btn:hover{border-color:var(--brand);color:var(--brand)}.empty-state{color:var(--muted);font-size:13px;padding:12px}.source-page{min-height:100vh;background:var(--bg);padding:32px}.source-page-card{max-width:1100px;margin:0 auto;background:#fff;border:1px solid var(--line);border-radius:8px;padding:24px}.source-page-head{display:flex;justify-content:space-between;gap:16px;align-items:flex-start;border-bottom:1px solid var(--line-soft);padding-bottom:16px;margin-bottom:18px}.source-page-head h1{margin:0 0 8px;font-size:20px}.source-page-head p{margin:0;color:var(--muted)}.source-page-viewer{min-height:520px;display:grid;place-items:center;background:#f8fafc;border:1px solid var(--line-soft);border-radius:8px;overflow:auto}.source-page-image{display:block;width:min(100%,980px);height:auto;background:#fff}.source-page-pdf{width:100%;height:720px;border:0;background:#fff}.source-page-empty,.source-page-error{color:var(--muted);font-size:14px;line-height:1.8;padding:24px;text-align:center}.source-page-error{color:#b91c1c;border:1px solid #fecaca;border-radius:8px;background:#fff1f2}@media(max-width:1180px){.workspace{grid-template-columns:220px 1fr}.sources{display:none}}