*{box-sizing:border-box;margin:0;padding:0}
body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;background:#f0f2f5;color:#1a1a2e;height:100vh;display:flex;flex-direction:column}
/* 顶栏 */
.header{background:#1a1a2e;color:#fff;padding:12px 24px;display:flex;align-items:center;justify-content:space-between;flex-shrink:0;box-shadow:0 2px 8px rgba(0,0,0,.15);z-index:10}
.header .brand{display:flex;align-items:center;gap:10px}
.header .brand svg{width:28px;height:28px}
.header .brand h1{font-size:18px;font-weight:600;margin:0}
.header .brand span{font-size:12px;color:#8a8aa0;margin-left:6px}
.header a{color:#1D4ED8;text-decoration:none;font-size:13px;padding:6px 14px;border:1px solid #1D4ED8;border-radius:6px;transition:.2s}
.header a:hover{background:#1D4ED8;color:#fff}
/* 主容器 */
.wrap{display:flex;flex:1;overflow:hidden;max-width:1200px;margin:0 auto;width:100%;padding:12px;gap:12px}
/* 侧栏 */
.sidebar{width:240px;background:#fff;border-radius:12px;display:flex;flex-direction:column;flex-shrink:0;box-shadow:0 1px 4px rgba(0,0,0,.06);overflow:hidden}
.sidebar-top{padding:14px 16px;font-weight:600;font-size:14px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid #f0f0f0}
.sidebar-top .new-btn{width:28px;height:28px;border-radius:6px;border:none;background:#1D4ED8;color:#fff;cursor:pointer;font-size:16px;display:flex;align-items:center;justify-content:center}
.session-list{flex:1;overflow-y:auto;padding:6px}
.session-item{padding:10px 12px;border-radius:8px;cursor:pointer;font-size:13px;margin-bottom:2px;transition:.15s;border-left:3px solid transparent}
.session-item:hover{background:#f5f5f8}
.session-item.active{background:#fff0f0;border-left-color:#1D4ED8}
.session-item .s-title{white-space:nowrap;overflow:hidden;text-overflow:ellipsis;font-size:13px}
.session-item .s-meta{font-size:11px;color:#999;margin-top:3px}
/* 主聊天区 */
.main-area{flex:1;display:flex;flex-direction:column;min-width:0;background:#fff;border-radius:12px;box-shadow:0 1px 4px rgba(0,0,0,.06);overflow:hidden}
/* 模式标签 */
.mode-bar{display:flex;gap:4px;padding:10px 20px;background:#fafafa;border-bottom:1px solid #f0f0f0;flex-shrink:0;flex-wrap:wrap}
.mode-tab{padding:6px 16px;border-radius:20px;border:1px solid #e0e0e0;background:#fff;cursor:pointer;font-size:13px;transition:.2s}
.mode-tab:hover{border-color:#1D4ED8;color:#1D4ED8}
.mode-tab.active{background:#1D4ED8;color:#fff;border-color:#1D4ED8}
/* 消息区 */
.messages{flex:1;overflow-y:auto;padding:24px 32px}
.message{max-width:780px;margin:0 auto 20px;display:flex;gap:12px}
.message.user{flex-direction:row-reverse}
.avatar{width:36px;height:36px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:15px;flex-shrink:0}
.avatar.ai{background:linear-gradient(135deg,#1D4ED8,#ff6b6b);color:#fff;font-weight:600}
.avatar.user{background:#16213e;color:#fff;font-weight:600}
.bubble{padding:14px 18px;border-radius:14px;font-size:14px;line-height:1.75;max-width:85%}
.message.ai .bubble{background:#f8f9fc;border:1px solid #eee;color:#1a1a2e}
.message.user .bubble{background:#1D4ED8;color:#fff}
.bubble p{margin:6px 0}
.bubble pre{background:#1e1e2e;color:#cdd6f4;border-radius:8px;padding:14px;overflow-x:auto;margin:10px 0;font-size:13px}
.bubble code{background:#f0f0f0;padding:2px 6px;border-radius:4px;font-size:13px}
.bubble pre code{background:transparent;padding:0;color:inherit}
.bubble ul,.bubble ol{padding-left:20px}
.bubble table{border-collapse:collapse;width:100%;margin:8px 0;font-size:13px}
.bubble td,.bubble th{border:1px solid #ddd;padding:6px 10px;text-align:left}
.bubble th{background:#f5f5f5}
.ref-block{font-size:12px;color:#888;margin-top:8px;padding-top:8px;border-top:1px solid #eee}
.ref-block span{display:inline-block;margin:2px 4px 2px 0;padding:2px 8px;background:#fff0f0;border-radius:4px;color:#1D4ED8}
/* 输入区 */
.input-area{padding:14px 24px;background:#fff;border-top:1px solid #f0f0f0;flex-shrink:0}
.input-row{max-width:780px;margin:0 auto;display:flex;gap:8px;align-items:center}
.input-row input{flex:1;padding:12px 18px;border:2px solid #e0e0e0;border-radius:24px;font-size:14px;outline:none;transition:.2s}
.input-row input::placeholder{color:#bbb}
.input-row input:focus{border-color:#1D4ED8;box-shadow:0 0 0 3px rgba(29,78,216,.1)}
.input-row button{width:42px;height:42px;border-radius:50%;background:#1D4ED8;color:#fff;border:none;cursor:pointer;font-size:16px;display:flex;align-items:center;justify-content:center;transition:.2s;flex-shrink:0}
.input-row button:hover{background:#d63850}
.input-row button:disabled{opacity:.5;cursor:not-allowed}
.typing{display:inline-flex;gap:4px;padding:6px 0}
.typing span{width:7px;height:7px;background:#999;border-radius:50%;animation:typing 1.4s infinite}
.typing span:nth-child(2){animation-delay:.2s}
.typing span:nth-child(3){animation-delay:.4s}
@keyframes typing{0%,60%,100%{opacity:.3}20%{opacity:1}}
/* 欢迎提示 */
.welcome-suggest{display:flex;gap:8px;flex-wrap:wrap;margin-top:10px}
.welcome-suggest button{background:#f8f9fc;border:1px solid #e0e0e0;border-radius:8px;padding:8px 14px;font-size:13px;cursor:pointer;color:#333;transition:.2s}
.welcome-suggest button:hover{border-color:#1D4ED8;color:#1D4ED8}
/* 错误提示 */
.err-toast{position:fixed;bottom:80px;left:50%;transform:translateX(-50%);background:#e74c3c;color:#fff;padding:10px 20px;border-radius:8px;font-size:13px;z-index:99;display:none;animation:fadeIn .3s}
@keyframes fadeIn{from{opacity:0;transform:translateX(-50%) translateY(10px)}to{opacity:1;transform:translateX(-50%) translateY(0)}}
.empty-state{text-align:center;padding:60px 20px;color:#bbb}
.empty-state .icon{font-size:48px;margin-bottom:12px}
.empty-state p{font-size:14px;margin:4px 0}
@media(max-width:768px){
.wrap{flex-direction:column;padding:8px;gap:8px}
.sidebar{width:100%;max-height:120px}
.messages{padding:16px}
.input-area{padding:10px 16px}
.mode-bar{padding:8px 12px}
}