:root {
  --bg: #0a1220;
  --panel: #0f1e35;
  --text: #e8eef7;
  --muted: #9db0c8;
  --accent: #4ad1a8;
  --user: #1f3a5d;
  --ai: #13253f;
  --border: #29466e;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  color: var(--text);
  font-family: "IBM Plex Sans", "Segoe UI", sans-serif;
  background: radial-gradient(circle at 10% 10%, #122746, var(--bg) 40%),
    linear-gradient(145deg, #08101c, #0d1a2f 60%, #0b1629);
  min-height: 100vh;
}

.shell {
  max-width: 940px;
  margin: 0 auto;
  padding: 24px 16px 36px;
}

.topbar h1 {
  margin: 0;
  font-size: 1.75rem;
}

.topbar p {
  margin: 10px 0 0;
  color: var(--muted);
}

.messages {
  margin-top: 20px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: color-mix(in srgb, var(--panel) 88%, black);
  min-height: 48vh;
  max-height: 62vh;
  overflow-y: auto;
  padding: 14px;
}

.msg {
  margin: 0 0 12px;
  padding: 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--ai);
}

.msg.user {
  background: var(--user);
}

.role {
  margin: 0 0 8px;
  font-size: 0.9rem;
  color: var(--accent);
}

.content {
  margin: 0;
  white-space: pre-wrap;
  font-family: "IBM Plex Sans", "Segoe UI", sans-serif;
  line-height: 1.45;
}

.composer {
  margin-top: 14px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--panel);
  padding: 10px;
}

textarea {
  width: 100%;
  resize: vertical;
  min-height: 84px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #0a1628;
  color: var(--text);
  padding: 10px;
  font: inherit;
}

.actions {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 8px;
}

button {
  border: 0;
  border-radius: 8px;
  padding: 10px 14px;
  background: var(--accent);
  color: #04231a;
  font-weight: 700;
  cursor: pointer;
}

button[disabled] {
  opacity: 0.65;
  cursor: not-allowed;
}

.status {
  color: var(--muted);
  font-size: 0.9rem;
}

@media (max-width: 720px) {
  .messages {
    min-height: 54vh;
    max-height: 58vh;
  }
  .topbar h1 {
    font-size: 1.4rem;
  }
}