:root{
  --bg:#0c0d10; --panel:#16171c; --line:#2b2d34; --text:#f3f1ea; --muted:#c4c0b4;
  --accent:#e2b13c; --ink:#111111; --danger:#c45c5c;
}
*{box-sizing:border-box}
html,body{margin:0;height:100%;background:var(--bg);color:var(--text);font-family:"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif}
a{color:var(--accent);text-decoration:none}
.app{display:flex;min-height:100%}
.side{width:260px;background:#101117;border-right:1px solid var(--line);padding:18px 14px;display:flex;flex-direction:column;gap:12px}
.side-brand{display:flex;gap:10px;align-items:center}
.brand-mark{width:52px;height:52px;border-radius:12px;background:var(--accent);color:var(--ink);display:flex;align-items:center;justify-content:center;font-weight:900;font-size:28px}
.brand-mark.sm{width:40px;height:40px;font-size:22px}
.tiny{color:var(--muted);font-size:12px}
.muted{color:var(--muted)}
.side-foot{margin-top:auto;display:flex;gap:14px}
.main{flex:1;display:flex;flex-direction:column;min-width:0}
.main.pad{padding:28px 32px}
.main-head{display:flex;justify-content:space-between;align-items:center;padding:18px 24px;border-bottom:1px solid var(--line)}
.main-head h1{margin:0;font-size:22px}
.chat{flex:1;overflow:auto;padding:20px 24px;display:flex;flex-direction:column;gap:12px}
.bubble{max-width:760px;padding:12px 14px;border-radius:14px;line-height:1.65;white-space:pre-wrap}
.bubble.user{align-self:flex-end;background:#2a2416;border:1px solid #4a3d1c}
.bubble.ai{align-self:flex-start;background:var(--panel);border:1px solid var(--line)}
.bubble .src{margin-top:8px;font-size:12px;color:var(--accent)}
.composer{display:flex;gap:10px;padding:14px 24px 20px;border-top:1px solid var(--line)}
.composer textarea{flex:1;background:#121318;color:var(--text);border:1px solid var(--line);border-radius:12px;padding:10px 12px;resize:none}
.btn-primary,.btn-ghost,.btn-danger,button[type=submit]{
  border:0;border-radius:999px;padding:10px 16px;font-weight:800;cursor:pointer
}
.btn-primary,button[type=submit]{background:var(--accent);color:var(--ink)}
.btn-ghost{background:#1c1e26;color:var(--text);border:1px solid var(--line);text-align:center}
.btn-danger{background:#3a1f1f;color:#ffd0d0;border:1px solid #5a3030}
.conv-list{display:flex;flex-direction:column;gap:6px;overflow:auto}
.conv-item{padding:8px 10px;border-radius:8px;color:var(--muted);cursor:pointer}
.conv-item:hover,.conv-item.on{background:#1c1e26;color:var(--text)}
.auth-body{display:flex;align-items:center;justify-content:center}
.auth-card{width:min(420px,92vw);background:var(--panel);border:1px solid var(--line);border-radius:20px;padding:32px;display:flex;flex-direction:column;gap:10px}
.auth-card h1{margin:8px 0 0}
.auth-card input{background:#121318;color:var(--text);border:1px solid var(--line);border-radius:10px;padding:10px}
.alert{background:#3a2a12;color:#f3d9a4;padding:8px 10px;border-radius:8px}
.upload-box{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:18px;display:flex;flex-direction:column;gap:8px;max-width:640px;margin:16px 0 28px}
.upload-box input{background:#121318;color:var(--text);border:1px solid var(--line);border-radius:10px;padding:10px}
.doc-card{display:flex;justify-content:space-between;gap:12px;align-items:flex-start;background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px;margin-bottom:10px}
.empty{color:var(--muted);padding:24px;border:1px dashed var(--line);border-radius:12px}
.library-app .side-foot{margin-top:auto}
@media(max-width:800px){.side{display:none}.composer{flex-direction:column}}

.auth-alt{margin:8px 0 0;text-align:center;color:var(--muted);font-size:14px}
.auth-alt a{font-weight:700}