:root{
  --bg:#ffffff;
  --ink:#0b1220;
  --muted:#6b7280;
  --line:#e8edf3;
  --shadow: 0 20px 60px rgba(12,15,20,.08);
  --radius: 22px;
}

*{box-sizing:border-box}
body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Arial;
  color:var(--ink);
  background:var(--bg);
}

.bg{
  position:fixed; inset:0; z-index:-2;
  background:
    radial-gradient(1200px 600px at 20% 15%, rgba(20,110,255,.10), transparent 55%),
    radial-gradient(900px 500px at 80% 25%, rgba(0,0,0,.06), transparent 55%),
    linear-gradient(#fff,#fff);
}

.topbar{
  display:flex; justify-content:space-between; align-items:center;
  padding:18px 26px;
}

.brand{display:flex; gap:12px; align-items:baseline}
.dot{
  width:8px;height:8px;border-radius:999px;
  background: rgba(20,110,255,.9);
  box-shadow: 0 0 0 6px rgba(20,110,255,.12);
  transform: translateY(-2px);
}
.name{letter-spacing:.14em; font-weight:700; font-size:13px}
.tag{color:var(--muted); font-size:13px}

.actions button{
  border:1px solid var(--line);
  background:transparent;
  padding:10px 14px;
  border-radius:999px;
  font-weight:600;
  cursor:pointer;
}

.shell{
  min-height: calc(100vh - 70px);
  display:flex; justify-content:center; align-items:center;
  padding:22px;
}

.panel{
  width:min(980px, 96vw);
  background: rgba(255,255,255,.85);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  backdrop-filter: blur(12px);
  padding: 18px;
  display:flex;
  flex-direction:column;
  gap: 14px;
}

.chat{
  height: min(62vh, 560px);
  overflow:auto;
  padding: 8px;
  display:flex;
  flex-direction:column;
  gap: 12px;
}

.msg{
  border:1px solid var(--line);
  background: rgba(255,255,255,.92);
  border-radius: 18px;
  padding: 14px 14px;
  max-width: 92%;
  white-space: pre-wrap;
}
.user{ align-self:flex-end; }
.ai{ align-self:flex-start; }

.composer{
  display:flex;
  gap:10px;
  border:1px solid var(--line);
  border-radius: 18px;
  padding: 10px;
  background: rgba(255,255,255,.92);
}

textarea{
  width:100%;
  border:none;
  outline:none;
  resize:none;
  font-size:15px;
  background:transparent;
  font-family: inherit;
  color:var(--ink);
}

.send{
  border:none;
  background:#111827;
  color:white;
  width:44px;
  height:44px;
  border-radius:14px;
  cursor:pointer;
  font-size:18px;
  font-weight:800;
}

.hint{ color:var(--muted); font-size:12px; padding: 0 6px 4px; }