:root {
  --bg: #f4f7fb;
  --surface: #ffffff;
  --ink: #1b2a41;
  --muted: #5d6b82;
  --line: #dfe6f0;
  --brand: #1f5fbf;
  --brand-ink: #ffffff;
  --brand-soft: #e8f0fc;
  --user: #1f5fbf;
  --danger: #b42318;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(20, 40, 80, .06), 0 4px 16px rgba(20, 40, 80, .06);
}

* { box-sizing: border-box; }

html, body { height: 100%; }

body {
  margin: 0;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--ink);
  font: 15px/1.7 -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  -webkit-text-size-adjust: 100%;
}

button { font: inherit; cursor: pointer; }

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 16px;
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}

.brand { display: flex; align-items: center; gap: 10px; min-width: 0; }
.brand img { flex: none; }
.brand h1 { margin: 0; font-size: 16px; line-height: 1.4; }
.brand p { margin: 0; font-size: 12px; color: var(--muted); }

.ghost {
  flex: none;
  padding: 6px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--ink);
}
.ghost:hover { border-color: var(--brand); color: var(--brand); }

.chat {
  flex: 1;
  overflow-y: auto;
  padding: 20px 16px 8px;
}

.welcome, .messages { max-width: 860px; margin: 0 auto; }

.welcome h2 { margin: 8px 0 4px; font-size: 20px; }
.welcome > p { margin: 0 0 16px; color: var(--muted); }

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 10px;
}

.card {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 14px;
  text-align: left;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--ink);
  box-shadow: var(--shadow);
}
.card strong { color: var(--brand); font-size: 15px; }
.card span { color: var(--muted); font-size: 13px; line-height: 1.5; }
.card:hover { border-color: var(--brand); }

.msg { display: flex; margin: 14px 0; }
.msg.user { justify-content: flex-end; }

.bubble {
  max-width: 100%;
  padding: 10px 14px;
  border-radius: var(--radius);
  overflow-wrap: anywhere;
}
.msg.user .bubble {
  max-width: 85%;
  background: var(--user);
  color: var(--brand-ink);
  white-space: pre-wrap;
}
.msg.bot .bubble {
  width: 100%;
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

.status { color: var(--muted); font-size: 13px; }
.status::after { content: "…"; animation: blink 1.2s steps(3) infinite; }
@keyframes blink { 50% { opacity: .3; } }
.error { color: var(--danger); }

/* Markdown 内容 */
.bubble > :first-child { margin-top: 0; }
.bubble > :last-child { margin-bottom: 0; }
.bubble h1, .bubble h2, .bubble h3, .bubble h4 { margin: 14px 0 6px; line-height: 1.4; }
.bubble h1 { font-size: 18px; }
.bubble h2 { font-size: 17px; }
.bubble h3, .bubble h4 { font-size: 15px; }
.bubble p { margin: 6px 0; }
.bubble ul, .bubble ol { margin: 6px 0; padding-left: 22px; }
.bubble a { color: var(--brand); word-break: break-all; }
.bubble code { padding: 1px 4px; border-radius: 4px; background: var(--brand-soft); font-size: 13px; }
.bubble pre {
  margin: 8px 0;
  padding: 10px 12px;
  overflow-x: auto;
  border-radius: 8px;
  background: #f6f8fb;
  border: 1px solid var(--line);
  white-space: pre-wrap;
}
.bubble pre code { padding: 0; background: none; }
.bubble blockquote { margin: 8px 0; padding: 2px 12px; border-left: 3px solid var(--brand); color: var(--muted); }
.table-wrap { overflow-x: auto; margin: 8px 0; }
.bubble table { border-collapse: collapse; min-width: 100%; font-size: 13px; }
.bubble th, .bubble td { padding: 6px 8px; border: 1px solid var(--line); vertical-align: top; text-align: left; }
.bubble th { background: var(--brand-soft); white-space: nowrap; }
.bubble video { display: block; width: 100%; max-width: 720px; margin: 10px 0; border-radius: 8px; background: #000; }

.composer {
  padding: 10px 16px calc(10px + env(safe-area-inset-bottom));
  background: var(--surface);
  border-top: 1px solid var(--line);
}
.composer form { display: flex; gap: 8px; max-width: 860px; margin: 0 auto; align-items: flex-end; }
.composer textarea {
  flex: 1;
  min-height: 42px;
  max-height: 40vh;
  padding: 9px 12px;
  resize: none;
  border: 1px solid var(--line);
  border-radius: 10px;
  font: inherit;
  color: var(--ink);
  background: var(--surface);
}
.composer textarea:focus { outline: 2px solid var(--brand-soft); border-color: var(--brand); }
.primary {
  flex: none;
  height: 42px;
  padding: 0 18px;
  border: 0;
  border-radius: 10px;
  background: var(--brand);
  color: var(--brand-ink);
}
.primary:disabled { opacity: .5; cursor: default; }
.primary.stop { background: var(--muted); }
.note { max-width: 860px; margin: 6px auto 0; color: var(--muted); font-size: 12px; text-align: center; }

@media (max-width: 560px) {
  .brand h1 { font-size: 14px; }
  .brand p { display: none; }
  .cards { grid-template-columns: 1fr 1fr; }
  .card { padding: 12px; }
  .note { display: none; }
}