您需要为标题栏添加一些 CSS，以将其保留在屏幕顶部并设置按钮样式：

.titlebar {
  height: 30px;
  background: #329ea3;
  user-select: none;
  display: flex;
  justify-content: flex-end;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
}
.titlebar-button {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  width: 30px;
  height: 30px;
}
.titlebar-button:hover {
  background: #5bbec3;
}