:root {
  color-scheme: dark;
  --bg: #05070d;
  --panel: #0d1320;
  --panel2: #111a2b;
  --text: #eef6ff;
  --muted: #94a3b8;
  --line: rgba(148, 163, 184, 0.22);
  --accent: #2fd6ff;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: radial-gradient(circle at top, rgba(47, 214, 255, 0.18), transparent 35%), var(--bg);
  color: var(--text);
}

.shell {
  width: min(900px, 100%);
  min-height: 100vh;
  margin: 0 auto;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.hero {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: 28px;
  background: linear-gradient(145deg, rgba(13, 19, 32, 0.95), rgba(17, 26, 43, 0.8));
}

.logo {
  width: 84px;
  height: 84px;
  display: block;
  border-radius: 22px;
  object-fit: cover;
  background: #000;
  box-shadow: 0 0 26px rgba(255, 255, 255, 0.08), 0 0 34px rgba(47, 214, 255, 0.12);
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 8vw, 4.5rem);
  line-height: 0.95;
}

.subtitle { margin: 8px 0 0; color: var(--muted); }

.messages {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: rgba(13, 19, 32, 0.68);
  overflow-y: auto;
}

.message {
  max-width: 88%;
  padding: 14px 16px;
  border-radius: 18px;
  line-height: 1.45;
  white-space: pre-wrap;
}

.message.user {
  align-self: flex-end;
  background: rgba(47, 214, 255, 0.16);
  border: 1px solid rgba(47, 214, 255, 0.28);
}

.message.assistant,
.message.system {
  align-self: flex-start;
  background: var(--panel2);
  border: 1px solid var(--line);
}

.message.error {
  background: rgba(251, 113, 133, 0.13);
  border: 1px solid rgba(251, 113, 133, 0.5);
}

.composer {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 12px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: rgba(13, 19, 32, 0.92);
}

textarea {
  width: 100%;
  resize: vertical;
  min-height: 66px;
  border: 0;
  border-radius: 16px;
  padding: 14px;
  background: #05070d;
  color: var(--text);
  font: inherit;
}

button {
  align-self: end;
  border: 0;
  border-radius: 16px;
  padding: 14px 18px;
  color: #001018;
  background: var(--accent);
  font-weight: 800;
}

button:disabled { opacity: 0.55; }

footer {
  color: var(--muted);
  text-align: center;
  font-size: 0.82rem;
}