:root{--bg: #ffffff;--bg-soft: #f5f6f8;--bg-sidebar: #f0f2f5;--border: #e3e6ea;--text: #1a1a1a;--muted: #8a9099;--accent: #2b7fff;--accent-text: #ffffff;--user-bubble: #2b7fff;--user-text: #ffffff;--error: #d64545;--radius: 12px}@media (prefers-color-scheme: dark){:root{--bg: #17181c;--bg-soft: #1f2026;--bg-sidebar: #131418;--border: #2c2e36;--text: #e8eaed;--muted: #7a8089;--accent: #3d8bff;--user-bubble: #2b6fd6;--user-text: #ffffff;--error: #ff6b6b}}*{box-sizing:border-box}html,body,#root{height:100%;margin:0}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;background:var(--bg);color:var(--text);font-size:15px;line-height:1.5}.muted{color:var(--muted)}.center{height:100%;display:flex;align-items:center;justify-content:center;padding:24px}.card{background:var(--bg-soft);border:1px solid var(--border);border-radius:var(--radius);padding:28px}.login{display:flex;flex-direction:column;gap:12px;width:320px}.login h1{font-size:20px;margin:0}.login p{margin:0 0 8px;font-size:13px}input,textarea{font:inherit;color:var(--text);background:var(--bg);border:1px solid var(--border);border-radius:8px;padding:10px 12px;outline:none;width:100%}input:focus,textarea:focus{border-color:var(--accent)}button{font:inherit;cursor:pointer;border:none;border-radius:8px;padding:10px 14px;background:var(--accent);color:var(--accent-text)}button:disabled{opacity:.5;cursor:default}button.link{background:none;color:var(--accent);padding:4px}.error{color:var(--error);font-size:13px}.layout{display:flex;height:100%}.sidebar{width:280px;flex-shrink:0;background:var(--bg-sidebar);border-right:1px solid var(--border);display:flex;flex-direction:column}.new-chat{margin:12px;background:var(--accent)}.chats{flex:1;overflow-y:auto;padding:0 8px}.chat-item{display:flex;align-items:center;gap:8px;padding:10px 12px;border-radius:8px;cursor:pointer}.chat-item:hover{background:var(--bg-soft)}.chat-item.active{background:var(--accent);color:var(--accent-text)}.chat-title{flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.chat-item .del{background:none;color:inherit;opacity:0;padding:0 4px;font-size:18px;line-height:1}.chat-item:hover .del{opacity:.6}.chat-item .del:hover{opacity:1}.empty-list{padding:16px 12px;font-size:13px}.user-bar{border-top:1px solid var(--border);padding:12px;display:flex;align-items:center;justify-content:space-between}.user-name{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.chat{flex:1;display:flex;flex-direction:column;min-width:0}.messages{flex:1;overflow-y:auto;padding:24px;display:flex;flex-direction:column;gap:12px}.msg{max-width:680px;padding:10px 14px;border-radius:var(--radius);white-space:pre-wrap;overflow-wrap:anywhere}.msg.user{align-self:flex-end;background:var(--user-bubble);color:var(--user-text)}.msg.assistant{align-self:flex-start;background:var(--bg-soft);border:1px solid var(--border)}.msg.assistant p:first-child{margin-top:0}.msg.assistant p:last-child{margin-bottom:0}.msg.assistant pre{background:var(--bg-sidebar);padding:12px;border-radius:8px;overflow-x:auto}.msg.error{align-self:flex-start;color:var(--error);background:none;border:1px solid var(--error)}.composer{display:flex;gap:8px;padding:16px 24px;border-top:1px solid var(--border);align-items:flex-end}.composer textarea{flex:1;resize:none;max-height:160px}.composer button{width:44px;height:40px;font-size:18px;flex-shrink:0}