:root{
  --bg:#f6f8fb;
  --card:#ffffff;
  --accent:#e6f0ff;
  --muted:#6b7280;
  --primary:#1f2937;
}
body{font-family:Inter,-apple-system,system-ui,Segoe UI,Roboto,'Helvetica Neue',Arial; background:var(--bg); color:var(--primary); margin:0;}
.topbar{background:#fff;padding:18px 28px;border-bottom:1px solid #eee;display:flex;align-items:center;justify-content:space-between}
h1{margin:0;font-size:20px}
.teacher-link{color:#2563eb;text-decoration:none}
.container{max-width:980px;margin:28px auto;padding:0 18px}
.chat-wrapper{background:var(--card);border-radius:10px;padding:18px;box-shadow:0 2px 6px rgba(16,24,40,0.04)}
.chat{min-height:360px;padding:10px; display:flex; flex-direction:column; gap:12px; overflow:auto; border:1px solid #f0f0f0; border-radius:8px}
.msg.user{align-self:flex-end;background:var(--accent);padding:12px;border-radius:12px;max-width:80%}
.msg.bot{align-self:flex-start;background:#eaf7ea;padding:12px;border-radius:12px;max-width:80%}
.controls{display:flex;gap:8px;margin-top:12px;align-items:center}
.controls input[type="text"], .controls input[type="number"], textarea, input{flex:1;padding:10px;border:2px solid #111; border-radius:8px; outline:none}
.controls button{padding:10px 12px;border-radius:8px;border:none;background:#fff;box-shadow:0 1px 0 rgba(16,24,40,0.04);cursor:pointer}
label{display:block;margin-top:8px;color:var(--muted)}
.hint{margin-top:12px;color:var(--muted)}
@media (max-width:600px){ .controls{flex-direction:column} }