你们看到的是容器的缺失边框颜色的。将 BorderBrush 值到蓝色什么是由 ItemContainerStyle $ C需要$ c>来删除白色寻找边界。

What you are seeing is a missing border color of the container. Set the BorderBrush value to the Blue for what is needed by the ItemContainerStyle to remove the White looking border.