:root{
  --bg:#0b1220;
  --panel:#111a2b;
  --panel-2:#0f1726;
  --border:#223047;
  --text:#e5eefb;
  --muted:#8ea2c3;
  --accent:#4f8cff;
  --accent-2:#2dd4bf;
  --danger:#ef4444;
  --bubble-user:#1d2d4b;
  --bubble-ai:#132033;
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family:system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Arial,sans-serif;
  background:linear-gradient(180deg,#08111d 0%, #0b1220 100%);
  color:var(--text);
}
.app{display:grid;grid-template-columns:340px 1fr;height:100vh}
.sidebar{
  background:rgba(17,26,43,.95);
  border-left:1px solid var(--border);
  padding:18px;
  display:flex;
  flex-direction:column;
  gap:18px;
}
.brand{display:flex;align-items:center;gap:12px}
.logo{
  width:48px;height:48px;border-radius:14px;
  display:grid;place-items:center;
  background:linear-gradient(135deg,var(--accent),var(--accent-2));
  font-weight:800;color:#fff;
}
.brand h1{margin:0;font-size:18px}
.brand p{margin:2px 0 0;color:var(--muted);font-size:12px}
.section h3{margin:0 0 10px;font-size:14px;color:#cfe0ff}
.list{display:flex;flex-direction:column;gap:8px;max-height:42vh;overflow:auto;padding-left:2px}
.conv{
  border:1px solid var(--border);background:var(--panel-2);color:var(--text);
  padding:12px;border-radius:14px;cursor:pointer;text-align:right
}
.conv.active{outline:2px solid rgba(79,140,255,.35)}
.conv .t{font-weight:600;font-size:13px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.conv .d{font-size:11px;color:var(--muted);margin-top:4px}
.auth-card{
  margin-top:auto;
  border-top:1px solid var(--border);
  padding-top:16px;
}
input,textarea{
  width:100%;
  border:1px solid var(--border);
  background:#0b1425;
  color:var(--text);
  border-radius:14px;
  padding:12px 14px;
  outline:none;
}
input:focus,textarea:focus{border-color:var(--accent)}
.row{display:flex;gap:10px}
.btn{
  border:1px solid var(--border);
  background:#16233a;
  color:var(--text);
  border-radius:14px;
  padding:11px 14px;
  cursor:pointer;
  font-weight:600;
}
.btn.primary{background:linear-gradient(135deg,var(--accent),#3b82f6);border-color:transparent}
.btn.ghost{background:transparent}
.chat{display:flex;flex-direction:column;height:100vh}
.topbar{
  padding:18px 22px;
  border-bottom:1px solid var(--border);
  background:rgba(11,18,32,.72);
  backdrop-filter:blur(10px);
}
.topbar h2{margin:0;font-size:18px}
.topbar p{margin:4px 0 0}
.muted{color:var(--muted);font-size:12px}
.messages{
  flex:1;
  overflow:auto;
  padding:24px;
  display:flex;
  flex-direction:column;
  gap:14px;
}
.msg{
  max-width:78%;
  padding:14px 16px;
  border:1px solid var(--border);
  border-radius:18px;
  line-height:1.7;
  white-space:pre-wrap;
  word-wrap:break-word;
}
.msg.user{align-self:flex-start;background:var(--bubble-user)}
.msg.ai{align-self:flex-end;background:var(--bubble-ai)}
.composer{
  border-top:1px solid var(--border);
  padding:16px;
  display:flex;
  gap:12px;
  background:rgba(17,26,43,.72);
}
.composer textarea{resize:none;min-height:56px;max-height:180px}
@media (max-width: 900px){
  .app{grid-template-columns:1fr}
  .sidebar{display:none}
  .msg{max-width:94%}
}