:root{
  --bg:#F5F6F8;
  --bg-white:#FFFFFF;
  --bg-soft:#F0F2F5;
  --line:#E5E8EE;
  --brand:#2A6DF5;
  --brand-soft:#EAF0FF;
  --txt:#1A1D24;
  --key:#5A6474;
  --muted:#98A1B0;
  --user-bg:#2A6DF5;
  --ai-bg:#FFFFFF;
  --danger:#E5484D;
  --ok:#22A06B;
}

*{box-sizing:border-box;-webkit-tap-highlight-color:transparent;}
html,body{
  margin:0;padding:0;height:100%;
  background:var(--bg);color:var(--txt);
  font-family:-apple-system,"PingFang SC","Noto Sans CJK SC",Roboto,sans-serif;
  overscroll-behavior:none;
}
button:focus,input:focus,textarea:focus{outline:none;}

/* 主区域 */
.main{
  position:fixed;left:0;right:0;top:0;bottom:0;
  display:flex;flex-direction:column;background:var(--bg);
}
.topbar{
  flex:0 0 auto;display:flex;align-items:center;
  height:52px;padding:0 6px;padding-top:env(safe-area-inset-top);
  border-bottom:1px solid var(--line);background:var(--bg-white);
}
.icon-btn{
  width:44px;height:44px;display:flex;align-items:center;justify-content:center;
  background:transparent;border:none;color:var(--txt);font-size:20px;cursor:pointer;border-radius:10px;
}
.icon-btn:active{background:var(--bg-soft);}
.topbar-title{
  flex:1;text-align:center;font-size:16px;font-weight:600;
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:var(--txt);
}

/* 消息区 */
.messages{
  flex:1 1 auto;overflow-y:auto;-webkit-overflow-scrolling:touch;
  padding:12px 12px 4px;
}
.msg{display:flex;flex-direction:column;align-items:flex-start;margin:10px 0;animation:fade .2s ease;}
@keyframes fade{from{opacity:0;transform:translateY(4px);}to{opacity:1;transform:none;}}
.msg.user{align-items:flex-end;}
.msg.ai{align-items:flex-start;}

.bubble{
  max-width:82%;padding:10px 13px;border-radius:16px;
  font-size:15px;line-height:1.55;
  white-space:pre-wrap;word-break:break-word;
  user-select:text;-webkit-user-select:text;outline:none;
}
.msg.user .bubble{
  background:var(--user-bg);color:#fff;
  border-bottom-right-radius:5px;align-self:flex-end;
}
.msg.ai .bubble{
  background:transparent;color:var(--txt);border:none;padding:0;border-radius:0;
  max-width:100%;width:100%;font-size:15.5px;line-height:1.8;white-space:normal;
}
.msg.ai .bubble p{margin:0 0 .9em;}
.msg.ai .bubble p:last-child{margin-bottom:0;}
.msg.ai .bubble h1,
.msg.ai .bubble h2,
.msg.ai .bubble h3,
.msg.ai .bubble h4{color:var(--txt);line-height:1.4;margin:1.1em 0 .55em;font-weight:700;}
.msg.ai .bubble h1{font-size:21px;border-bottom:1px solid var(--line);padding-bottom:.25em;}
.msg.ai .bubble h2{font-size:18.5px;border-bottom:1px solid var(--line);padding-bottom:.2em;}
.msg.ai .bubble h3{font-size:16.5px;}
.msg.ai .bubble h4{font-size:15.5px;color:var(--key);}
.msg.ai .bubble h1:first-child,
.msg.ai .bubble h2:first-child,
.msg.ai .bubble h3:first-child{margin-top:0;}
.msg.ai .bubble ul,
.msg.ai .bubble ol{margin:0 0 .9em;padding-left:1.5em;}
.msg.ai .bubble li{margin:.25em 0;}
.msg.ai .bubble blockquote{
  margin:.9em 0;padding:.4em .9em;border-left:3px solid var(--brand);
  background:var(--bg-soft);color:var(--key);border-radius:0 8px 8px 0;
}
.msg.ai .bubble hr{border:none;border-top:1px solid var(--line);margin:1.2em 0;}
.msg.ai .bubble a{color:var(--brand);text-decoration:none;}
.msg.ai .bubble.err{color:var(--danger);background:#FFF6F6;border-radius:10px;padding:10px 13px;}

.code-block{position:relative;margin:10px 0;}
.code-block pre{
  background:#F7F8FA;border:1px solid var(--line);padding:12px;border-radius:10px;
  overflow-x:auto;font-family:ui-monospace,Menlo,monospace;font-size:13px;margin:0;
}
.copy-btn{
  position:absolute;top:6px;right:6px;
  background:rgba(255,255,255,.92);border:1px solid var(--line);
  color:var(--key);font-size:11px;font-family:inherit;
  padding:3px 8px;border-radius:7px;cursor:pointer;
  -webkit-user-select:none;user-select:none;
}
.copy-btn:active{background:var(--brand-soft);border-color:var(--brand);color:var(--brand);}

.table-block{position:relative;margin:10px 0;overflow-x:auto;}
.table-block table{border-collapse:collapse;width:100%;font-size:13px;}
.table-block th,.table-block td{
  border:1px solid var(--line);padding:6px 9px;text-align:left;white-space:nowrap;
}
.table-block th{background:var(--bg-soft);font-weight:600;}
.table-block .copy-btn{top:4px;right:4px;}

.msg-foot{margin:4px 0 2px;display:block;width:auto;}
.msg-foot .copy-btn{
  position:static;display:inline-block;width:auto;
  background:transparent;border:1px solid var(--line);
  color:var(--muted);font-size:12px;padding:4px 12px;border-radius:16px;
  font-family:inherit;cursor:pointer;
}
.msg-foot .copy-btn:active{background:var(--brand-soft);border-color:var(--brand);color:var(--brand);}

.bubble code{background:rgba(0,0,0,.06);padding:1px 5px;border-radius:5px;font-family:ui-monospace,Menlo,monospace;font-size:13px;}
.bubble pre{background:#F7F8FA;border:1px solid var(--line);padding:10px;border-radius:10px;overflow-x:auto;font-family:ui-monospace,Menlo,monospace;font-size:13px;margin:8px 0;}

.typing{display:inline-block;height:20px;line-height:20px;}
.typing i{
  display:inline-block;vertical-align:middle;width:6px;height:6px;border-radius:50%;
  background:var(--muted);margin-right:4px;animation:bl 1.2s infinite;
}
.typing i:nth-child(2){animation-delay:.2s;}
.typing i:nth-child(3){animation-delay:.4s;margin-right:0;}
@keyframes bl{0%,60%,100%{opacity:.25;}30%{opacity:1;}}
.wait-tip{color:var(--muted);font-size:12px;margin-left:6px;vertical-align:middle;}

.welcome{text-align:center;padding:40px 20px 20px;}
.welcome-logo{font-size:40px;color:var(--brand);margin-bottom:12px;}
.welcome-title{font-size:20px;font-weight:600;margin-bottom:6px;}
.welcome-sub{font-size:13px;color:var(--key);margin-bottom:24px;}
.chips{display:block;text-align:center;margin:-4px;}
.chip{
  display:inline-block;margin:4px;padding:8px 14px;border-radius:20px;
  border:1px solid var(--line);background:var(--bg-white);
  color:var(--key);font-size:13px;cursor:pointer;
}
.chip:active{border-color:var(--brand);color:var(--brand);}

/* 输入区 */
.composer{
  flex:0 0 auto;padding:6px 14px;
  padding-bottom:calc(10px + env(safe-area-inset-bottom));
  background:var(--bg-white);border-top:1px solid var(--line);
}
.input-wrap{width:100%;}
.input{
  display:block;width:100%;resize:none;min-height:40px;max-height:132px;
  padding:8px 2px;background:transparent;border:none;border-radius:0;
  color:var(--txt);font-size:16px;font-family:inherit;line-height:1.5;
  outline:none;overflow-y:auto;-webkit-appearance:none;
  caret-color:var(--brand);box-shadow:none;
}
.input::placeholder{color:var(--muted);}
.input:focus{background:transparent;border:none;box-shadow:none;}
.input::-webkit-scrollbar{width:0;height:0;display:none;}
.input{scrollbar-width:none;-ms-overflow-style:none;}

.toolbar{
  display:flex;align-items:center;justify-content:space-between;
  margin-top:6px;min-height:38px;
}
.toolbar-left{display:flex;align-items:center;min-width:0;flex:1 1 auto;}

.send-btn{
  flex:0 0 auto;width:38px;height:38px;margin-left:8px;
  border:none;border-radius:50%;background:var(--user-bg);color:#fff;
  font-size:18px;font-weight:700;
  display:flex;align-items:center;justify-content:center;cursor:pointer;
  box-shadow:0 2px 8px rgba(42,109,245,.28);
  transition:transform .12s,background .15s,box-shadow .15s,color .15s;
}
.send-btn:disabled{background:var(--bg-soft);color:var(--muted);box-shadow:none;cursor:default;}
.send-btn:active:not(:disabled){transform:scale(.92);}
.send-btn.stop{background:var(--txt);box-shadow:0 2px 8px rgba(0,0,0,.18);font-size:14px;}

/* 抽屉 */
.mask{
  position:fixed;left:0;right:0;top:0;bottom:0;background:rgba(0,0,0,.35);
  opacity:0;visibility:hidden;transition:opacity .25s;z-index:40;
}
.mask.show{opacity:1;visibility:visible;}
.drawer{
  position:fixed;top:0;left:0;bottom:0;width:80%;max-width:320px;
  background:var(--bg-white);border-right:1px solid var(--line);
  transform:translateX(-102%);visibility:hidden;
  transition:transform .27s cubic-bezier(.22,.61,.36,1),visibility .27s;
  z-index:50;display:flex;flex-direction:column;padding-top:env(safe-area-inset-top);
}
.drawer.show{transform:none;visibility:visible;}
.drawer-head{padding:12px 12px 6px;}
.drawer-title-row{display:flex;align-items:center;justify-content:space-between;height:34px;}
.drawer-title{font-size:13px;color:var(--muted);letter-spacing:.5px;}
.drawer-sel-btn{
  background:transparent;border:none;cursor:pointer;
  color:var(--brand);font-size:13px;font-family:inherit;padding:4px 8px;border-radius:8px;
}
.drawer-sel-btn:active{background:var(--bg-soft);}
.drawer-selbar{display:none;align-items:center;justify-content:space-between;height:38px;margin-top:2px;}
.drawer-selbar.show{display:flex;}
.selbar-cancel{background:transparent;border:none;cursor:pointer;color:var(--muted);font-size:13px;font-family:inherit;padding:4px 8px;border-radius:8px;}
.selbar-cancel:active{background:var(--bg-soft);}
.selbar-count{font-size:13px;color:var(--key);}
.selbar-del{background:transparent;border:none;cursor:pointer;color:#e5484d;font-size:13px;font-weight:600;font-family:inherit;padding:4px 10px;border-radius:8px;}
.selbar-del:active{background:var(--bg-soft);}
.selbar-del:disabled{color:var(--muted);opacity:.5;}
.topic-list{flex:1;overflow-y:auto;-webkit-overflow-scrolling:touch;padding:0 8px;}
.topic-item{
  display:block;padding:11px 12px;margin:2px 0;border-radius:10px;cursor:pointer;
  color:var(--key);font-size:14px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;
}
.topic-item:active{background:var(--bg-soft);}
.topic-item.active{background:var(--brand-soft);color:var(--brand);}
.topic-item.selectable{padding-left:38px;position:relative;}
.topic-item.selectable::before{
  content:"";position:absolute;left:14px;top:50%;width:16px;height:16px;margin-top:-8px;
  border-radius:50%;border:1.5px solid var(--line);background:#fff;
}
.topic-item.selected{background:var(--brand-soft);}
.topic-item.selected::before{
  content:"\2713";border-color:var(--brand);background:var(--brand);color:#fff;
  font-size:11px;line-height:16px;text-align:center;
}
.topic-empty{padding:20px 12px;color:var(--muted);font-size:13px;text-align:center;}

/* Toast */
.toast{
  position:fixed;left:50%;bottom:90px;transform:translateX(-50%) translateY(10px);
  background:rgba(0,0,0,.85);color:#fff;padding:10px 18px;border-radius:20px;
  font-size:13px;max-width:80%;text-align:center;
  opacity:0;transition:opacity .2s,transform .2s;z-index:99;pointer-events:none;
}
.toast.show{opacity:1;transform:translateX(-50%);}

/* 思考过程 */
.reasoning{
  width:100%;margin:0 0 8px;border:1px solid var(--line);border-radius:10px;
  background:var(--bg-soft);overflow:hidden;
}
.reasoning>summary{
  list-style:none;cursor:pointer;padding:8px 12px;font-size:13px;
  color:var(--key);-webkit-user-select:none;user-select:none;
}
.reasoning>summary::-webkit-details-marker{display:none;}
.reasoning>summary::after{content:'▾';float:right;color:var(--muted);transition:transform .2s;}
.reasoning[open]>summary::after{transform:rotate(180deg);}
.reasoning-title{font-weight:600;}
.reasoning.live .reasoning-title::after{
  content:'';display:inline-block;width:6px;height:6px;border-radius:50%;
  background:var(--brand);margin-left:6px;vertical-align:middle;animation:bl 1.2s infinite;
}
.reasoning-body{
  padding:2px 12px 10px;border-top:1px solid var(--line);color:var(--key);
  font-size:13.5px;line-height:1.7;white-space:normal;word-break:break-word;
  max-height:40vh;overflow-y:auto;-webkit-overflow-scrolling:touch;
}
.reasoning.live .reasoning-body{max-height:calc(1.7em * 5 + 10px);}
.reasoning.done[open] .reasoning-body{max-height:40vh;}

/* ===== 工具按钮（工具栏左侧：自动朗读开关等） ===== */
.tool-btn{
  flex:0 0 auto;
  width:32px;height:32px;
  margin-left:0;
  padding:0;
  border-radius:50%;
  border:1px solid var(--line);
  background:var(--bg-white);
  color:var(--key);
  display:flex;align-items:center;justify-content:center;
  cursor:pointer;
  -webkit-tap-highlight-color:transparent;
  transition:border-color .15s,color .15s,background .15s;
}
.tool-btn svg{display:block;}
.tool-btn:active{
  background:var(--brand-soft);
  border-color:var(--brand);
  color:var(--brand);
}
.tool-btn.on{
  background:var(--brand-soft);
  border-color:var(--brand);
  color:var(--brand);
}
.tool-btn[hidden]{display:none!important;}

/* ===== 消息底部：朗读 / 复制 按钮 ===== */
.msg-foot .tts-btn{
  position:static;display:inline-block;width:auto;
  background:transparent;border:1px solid var(--line);
  color:var(--muted);font-size:12px;
  padding:4px 12px;border-radius:16px;
  font-family:inherit;cursor:pointer;
  margin-right:8px;
  -webkit-user-select:none;user-select:none;
}
.msg-foot .tts-btn:active,
.msg-foot .tts-btn.speaking{
  background:var(--brand-soft);
  border-color:var(--brand);
  color:var(--brand);
}
.msg-foot .tts-btn[hidden]{display:none!important;}