:root {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --muted: #666;
  --bubble-user: #2563eb;
  --bubble-bot: #f1f2f4;
  --border: #e2e2e2;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121214;
    --fg: #f0f0f0;
    --muted: #a1a1a1;
    --bubble-bot: #232326;
    --border: #2e2e32;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

.shell {
  max-width: 680px;
  margin: 0 auto;
  padding: 24px 16px 40px;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.hero h1 { margin: 0 0 8px; font-size: 1.6rem; }
.sub { margin: 0 0 12px; color: var(--muted); }
.pill {
  display: inline-block;
  font-size: 0.8rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 4px 12px;
  color: var(--muted);
  margin: 0;
}

.chat {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 20px 0;
  overflow-y: auto;
}

.msg {
  max-width: 85%;
  padding: 10px 14px;
  border-radius: 16px;
  line-height: 1.45;
  white-space: pre-wrap;
  word-break: break-word;
}

.msg.user { align-self: flex-end; background: var(--bubble-user); color: #fff; }
.msg.bot { align-self: flex-start; background: var(--bubble-bot); color: var(--fg); }
.msg.error { align-self: flex-start; background: transparent; border: 1px solid #e05353; color: #e05353; }
.msg.typing { opacity: 0.6; font-style: italic; }

.msg.ad {
  align-self: flex-start;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 12px;
}
.ad-label {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin-bottom: 4px;
}
.ad-head { font-weight: 600; margin-bottom: 4px; }
.ad-text { font-size: 0.9rem; margin-bottom: 8px; }
.ad-cta {
  display: inline-block;
  padding: 6px 14px;
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: 8px;
  background: var(--bubble-user);
  color: #fff;
  text-decoration: none;
}
.msg.ad img { position: absolute; visibility: hidden; }
.msg.ad.clickable { cursor: pointer; }
.ad-imp { position: absolute; visibility: hidden; }

.msg.bot p { margin: 0 0 8px; }
.msg.bot p:last-child { margin-bottom: 0; }
.msg.bot pre {
  background: rgba(128, 128, 128, 0.15);
  border-radius: 8px;
  padding: 10px 12px;
  overflow-x: auto;
  font-size: 0.85rem;
}
.msg.bot code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 0.85em; }
.msg.bot ul { margin: 0 0 8px; padding-left: 20px; }
.msg.bot h3, .msg.bot h4, .msg.bot h5 { margin: 8px 0 4px; font-size: 1rem; }
.msg.bot a { color: var(--bubble-user); }

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 10px;
}
.chip {
  padding: 8px 14px;
  font-size: 0.85rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: transparent;
  color: var(--fg);
  cursor: pointer;
}
.chip:hover { border-color: var(--bubble-user); color: var(--bubble-user); }

.composer { display: flex; gap: 8px; }
.composer input {
  flex: 1;
  padding: 12px 14px;
  font-size: 1rem;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--bg);
  color: var(--fg);
}
.composer button {
  padding: 0 20px;
  font-size: 1rem;
  border: 0;
  border-radius: 12px;
  background: var(--bubble-user);
  color: #fff;
  cursor: pointer;
}
.composer button:disabled { opacity: 0.5; cursor: default; }

.hint { color: var(--muted); font-size: 0.8rem; }
.hint code { font-size: 0.8rem; }