body::after {
  content: "LOCAL MIRROR LAB  ·  非官方教学实验 · 本地模拟数据";
  position: fixed;
  bottom: 10px;
  right: 16px;
  z-index: 2147483647;
  padding: 7px 12px;
  border: 1px solid #d5dadd;
  border-radius: 20px;
  background: #f4f7f9ee;
  color: #51616d;
  font: 11px/1.4 system-ui, sans-serif;
  pointer-events: none;
}
body[data-gateway-mode="web-session"]::after {
  content: "MIRROR LAB · 非官方 · 授权网页会话（内容发送至 ChatGPT）";
}
body[data-gateway-mode="xyhelper-core"]::after {
  content: "MIRROR LAB · 非官方 · XYHELPER 网页账号接入 · 勿输入敏感信息";
}
@media (max-width: 640px) {
  body::after { font-size: 9px; right: 8px; bottom: 5px; padding: 4px 8px; }
}