* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", "PingFang TC", "Microsoft JhengHei", sans-serif;
  background: #f0f2f5;
  color: #1c1c1e;
}

.chat {
  max-width: 640px;
  margin: 0 auto;
  height: 100vh;
  display: flex;
  flex-direction: column;
  background: #fff;
}

.chat__header {
  padding: 16px 20px;
  font-weight: 600;
  font-size: 17px;
  color: #fff;
  background: #2b6cb0;
}

.chat__messages {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.msg {
  max-width: 85%;
  padding: 10px 14px;
  border-radius: 14px;
  line-height: 1.6;
  white-space: normal;
  word-break: break-word;
}

.msg--bot {
  align-self: flex-start;
  background: #eef1f5;
  border-bottom-left-radius: 4px;
}

.msg--user {
  align-self: flex-end;
  background: #2b6cb0;
  color: #fff;
  border-bottom-right-radius: 4px;
}

.msg h1, .msg h2, .msg h3 { margin: 0.6em 0 0.3em; line-height: 1.3; }
.msg h1 { font-size: 1.25em; }
.msg h2 { font-size: 1.12em; }
.msg h3 { font-size: 1.02em; }
.msg p { margin: 0.5em 0; }
.msg ul, .msg ol { margin: 0.4em 0; padding-left: 1.4em; }
.msg li { margin: 0.2em 0; }
.msg blockquote {
  margin: 0.5em 0;
  padding: 0.3em 0.8em;
  border-left: 3px solid #b4c4d8;
  color: #555;
}
.msg code { background: #dde3ea; padding: 1px 5px; border-radius: 4px; font-size: 0.92em; }

.chat__choices {
  padding: 12px 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  border-top: 1px solid #e5e7eb;
  max-height: 40vh;
  overflow-y: auto;
}

.choice {
  border: 1px solid #2b6cb0;
  color: #2b6cb0;
  background: #fff;
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 14px;
  text-align: left;
  cursor: pointer;
}
.choice:hover { background: #2b6cb0; color: #fff; }
.choice--back {
  border-color: #999;
  color: #666;
  align-self: flex-start;
  border-radius: 18px;
}
.choice--back:hover { background: #666; color: #fff; }