:root{color-scheme:light;--bg:#f3f5f8;--card:#fff;--line:#dfe4eb;--text:#263241;--muted:#788493;--accent:#5379ad;--accent-soft:#e9f0fa;--danger:#b85c68;--shadow:0 16px 40px #31415b12}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text);font-family:-apple-system,BlinkMacSystemFont,"SF Pro Display","Hiragino Sans",sans-serif}body.dark{color-scheme:dark;--bg:#202632;--card:#2a3340;--line:#404b5a;--text:#edf2f7;--muted:#a8b3c1;--accent:#93b6e8;--accent-soft:#344761;--shadow:0 16px 40px #0004}button,input,textarea,select{font:inherit}button{cursor:pointer;border:1px solid var(--line);background:var(--card);color:var(--text);border-radius:10px}svg{width:20px;height:20px;display:block;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}.app{width:min(1440px,100%);margin:auto;padding:24px}.top{display:flex;align-items:center;justify-content:space-between;margin-bottom:20px}.brand{display:flex;align-items:center;gap:12px}.brand-mark{width:48px;height:48px;display:grid;place-items:center;border-radius:12px;background:var(--accent-soft);color:var(--accent)}.brand-mark svg{width:27px;height:27px}.brand h1{font-size:20px;margin:0}.brand p{font-size:12px;color:var(--muted);margin:4px 0 0}.top-actions{display:flex;gap:8px}.icon-btn{width:48px;height:48px;display:grid;place-items:center;font-size:20px}.card{background:var(--card);border:1px solid var(--line);border-radius:16px;box-shadow:var(--shadow)}.login{max-width:440px;margin:15vh auto;padding:40px;text-align:center}.lock{color:var(--accent);margin-bottom:14px}.lock svg{width:30px;height:30px;margin:auto}.login h2{margin:0 0 8px}.login p{color:var(--muted);margin:0 0 24px}.login form{display:grid;gap:12px}.login input,.title-input,.workspace select,#composer textarea{width:100%;border:1px solid var(--line);background:var(--bg);color:var(--text);border-radius:10px;padding:12px;outline:none}.login form button,.send{background:var(--accent);color:white;border:0;padding:12px 18px}.login small{color:var(--danger);min-height:18px}.layout{display:grid;grid-template-columns:240px minmax(0,1fr) 280px;gap:16px;min-height:calc(100vh - 120px)}.sidebar,.workspace,.conversation{min-height:560px;overflow:hidden}.sidebar,.workspace{padding:16px}.side-head,.conversation-head,.compose-foot{display:flex;align-items:center;justify-content:space-between;gap:10px}.small-btn{width:40px;height:40px;color:var(--accent);display:grid;place-items:center}.chat-list{display:grid;gap:6px;margin-top:14px}.chat-item{padding:12px;border:1px solid transparent;border-radius:10px;cursor:pointer;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.chat-item:hover,.chat-item.active{background:var(--accent-soft);color:var(--accent)}.conversation{display:flex;flex-direction:column}.conversation-head{padding:14px 16px;border-bottom:1px solid var(--line)}.title-input{background:transparent;border-color:transparent;font-weight:600;padding:5px 8px;width:min(420px,60vw)}.title-input:focus{border-color:var(--line)}.conversation-head small{display:block;color:var(--muted);padding-left:8px;margin-top:3px}.messages{flex:1;overflow:auto;padding:24px;display:grid;align-content:start;gap:18px}.message{max-width:88%;padding:14px 16px;border-radius:14px;white-space:pre-wrap;line-height:1.6}.message.user{justify-self:end;background:var(--accent);color:white}.message.assistant{justify-self:start;background:var(--accent-soft)}.message .role{font-size:11px;opacity:.7;margin-bottom:5px}.message code{font-family:ui-monospace,monospace;background:#0002;padding:2px 4px;border-radius:4px}.message a{color:inherit;text-decoration:underline}.message strong{font-weight:700}.#composer{padding:14px 16px;border-top:1px solid var(--line)}#composer textarea{resize:vertical;min-height:72px;display:block}.compose-foot{margin-top:10px;justify-content:flex-end}.attach-btn{width:40px;height:40px;border:1px solid var(--line);border-radius:10px;display:grid;place-items:center;color:var(--accent);cursor:pointer}.secondary{padding:10px 14px}.send{border-radius:10px;padding:10px 18px}.attachments{padding:0 16px;display:flex;gap:6px;flex-wrap:wrap}.attachment{font-size:12px;background:var(--accent-soft);padding:6px 9px;border-radius:8px}.workspace{display:flex;flex-direction:column;gap:12px}.workspace textarea{height:220px;resize:vertical;font-family:ui-monospace,monospace;font-size:12px}.workspace pre{flex:1;white-space:pre-wrap;background:#111827;color:#d6e2f2;padding:12px;border-radius:10px;overflow:auto;font-size:12px;margin:0}.muted{font-size:11px;color:var(--muted)}.danger{color:var(--danger)}@media(max-width:1000px){.layout{grid-template-columns:200px minmax(0,1fr)}.workspace{grid-column:1/-1;min-height:260px}.workspace textarea{height:120px}}@media(max-width:680px){.app{padding:12px}.layout{display:flex;flex-direction:column;min-height:calc(100vh - 100px)}.sidebar{min-height:unset;max-height:150px}.chat-list{display:flex;overflow:auto}.chat-item{min-width:160px}.conversation{min-height:calc(100vh - 330px)}.workspace{min-height:280px}.login{margin:10vh auto;padding:28px 20px}.messages{padding:16px}.message{max-width:96%}}