:root {
  color-scheme: light dark;
  --bg: #f5f4f0;
  --fg: #1c1b1a;
  --bubble-user: #2b6cb0;
  --bubble-user-fg: #fff;
  --bubble-bot: #fff;
  --bubble-bot-fg: #1c1b1a;
  --border: #ddd8d0;
  --muted: #6b6558;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17191c;
    --fg: #eae7e1;
    --bubble-user: #3b7dd8;
    --bubble-user-fg: #fff;
    --bubble-bot: #24272b;
    --bubble-bot-fg: #eae7e1;
    --border: #33363a;
    --muted: #9a9488;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--fg);
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  display: flex;
  justify-content: center;
}

.chat {
  width: 100%;
  max-width: 640px;
  display: flex;
  flex-direction: column;
  height: 100vh;
  padding: 1rem;
}

.chat-header h1 {
  margin: 0 0 0.25rem;
  font-size: 1.4rem;
}

.chat-header p {
  margin: 0 0 1rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.messages {
  flex: 1;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  padding: 0.5rem 0;
}

.bubble {
  max-width: 85%;
  padding: 0.6rem 0.9rem;
  border-radius: 0.9rem;
  line-height: 1.4;
  white-space: pre-wrap;
  word-break: break-word;
}

.bubble.user {
  align-self: flex-end;
  background: var(--bubble-user);
  color: var(--bubble-user-fg);
  border-bottom-right-radius: 0.2rem;
}

.bubble.bot {
  align-self: flex-start;
  background: var(--bubble-bot);
  color: var(--bubble-bot-fg);
  border: 1px solid var(--border);
  border-bottom-left-radius: 0.2rem;
}

.chat-form {
  display: flex;
  gap: 0.5rem;
  border-top: 1px solid var(--border);
  padding-top: 0.75rem;
}

#chat-input {
  flex: 1;
  resize: none;
  border: 1px solid var(--border);
  border-radius: 0.6rem;
  padding: 0.6rem 0.8rem;
  font: inherit;
  background: var(--bubble-bot);
  color: var(--fg);
  max-height: 6rem;
}

#send-btn {
  border: none;
  border-radius: 0.6rem;
  padding: 0 1.2rem;
  background: var(--bubble-user);
  color: #fff;
  font: inherit;
  cursor: pointer;
}

#send-btn:disabled {
  opacity: 0.5;
  cursor: default;
}

.status {
  min-height: 1.2rem;
  margin: 0.4rem 0 0;
  font-size: 0.8rem;
  color: var(--muted);
}