:root{--bg:#F7F2EA;--ink:#2A2118;--muted:#7E7265;--accent:#A55A15;--line:#e5d9c9;--card:#fff;--bad:#B42318;--you:#F1E6D6}
@media (prefers-color-scheme:dark){:root{--bg:#1d1a16;--ink:#f1ebe2;--muted:#a89c8e;--accent:#E0A15E;--line:#3a332b;--card:#26221d;--you:#3a3026}}
*{box-sizing:border-box}html,body{height:100%}
body{margin:0;font:16px/1.5 system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;color:var(--ink);background:var(--bg)}
.app{display:flex;flex-direction:column;height:100%}
.top{display:flex;align-items:center;gap:12px;padding:8px 16px;border-bottom:1px solid var(--line);background:var(--card)}
.top b{flex:1}.top span{color:var(--muted);font-size:14px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
button,input,textarea{font:inherit;color:inherit}
.top button,.chat button.ghost,.tabs button{padding:6px 12px;border:1px solid var(--line);border-radius:8px;background:none;cursor:pointer}
.main{flex:1;min-height:0;display:grid;grid-template-columns:minmax(300px,420px) minmax(0,1fr)}
.chat{display:flex;flex-direction:column;min-height:0;border-right:1px solid var(--line);background:var(--card)}
#msgs{flex:1;overflow:auto;padding:14px;display:flex;flex-direction:column;gap:10px}
.msg{max-width:92%;padding:8px 12px;border-radius:12px;border:1px solid var(--line)}
.msg.us{align-self:flex-start;background:var(--bg)}.msg.you{align-self:flex-end;background:var(--you)}
.msg .who{font-size:12px;color:var(--muted);font-weight:600}.msg .txt{white-space:pre-wrap;overflow-wrap:anywhere}
#chatform{border-top:1px solid var(--line);padding:10px;display:grid;gap:6px}
#chatbox{width:100%;min-height:64px;max-height:160px;resize:vertical;padding:10px;border:1px solid var(--line);border-radius:10px;background:var(--bg)}
.row{display:flex;gap:8px;align-items:center}.row .grow{flex:1}
.note{font-size:13px;color:var(--muted)}
.draw{display:flex;flex-direction:column;min-width:0;min-height:0}
.tabs{display:flex;gap:6px;align-items:center;padding:8px 12px;border-bottom:1px solid var(--line);flex-wrap:wrap}
.tabs button[aria-selected="true"]{background:var(--bg);font-weight:600}
.tabs .grow{flex:1}
iframe#tool{flex:1;width:100%;border:0;background:var(--card)}
#signdlg{position:fixed;inset:0;display:grid;place-items:center;background:rgba(0,0,0,.4);z-index:60}
#signdlg[hidden]{display:none}
#signdlg .box{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:20px;width:min(360px,92vw);display:grid;gap:10px}
#signdlg input{padding:10px;border:1px solid var(--line);border-radius:8px;background:var(--bg)}
#signdlg input[hidden]{display:none}
@media (max-width:820px){.main{grid-template-columns:1fr;grid-template-rows:minmax(240px,45%) minmax(0,1fr)}.chat{border-right:0;border-bottom:1px solid var(--line)}}

.login{flex:1;display:grid;place-items:center;padding:20px}.login[hidden],.main[hidden],.draw[hidden]{display:none}
.login .card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:24px;width:min(380px,100%);display:grid;gap:10px}
.login h1{margin:0;font-size:22px}.login input{padding:10px;border:1px solid var(--line);border-radius:8px;background:var(--bg)}.login input[hidden]{display:none}
.numbox{text-align:center}.bignum{font-size:44px;font-weight:700;letter-spacing:10px;margin:6px 0}
.primary{padding:8px 16px;border:0;border-radius:8px;background:var(--accent);color:#fff;cursor:pointer}.primary:disabled{opacity:.6}
.pic{display:block;max-width:100%;max-height:340px;border-radius:8px;margin-top:6px}.file{display:block;margin-top:6px;color:var(--accent)}
.main:not(.withtools){grid-template-columns:minmax(0,760px);justify-content:center}.main:not(.withtools) .chat{border-right:0}