如图：
两处checkbox实现的文件位置：
screenshot of checkbox class in user-form.component.html:
screenshot for checkbox in unit-user-role.component.html:
html source code and css style for checkbox in user form:
html source code and css style for checkbox in unit-user-role html:
I have compared both, and no difference found between the two.
视觉效果上的差异：
