I found some bugs in layout of question page for tags as below.
If I move the mouse to the tag on a question page the background color blue will exceed the tag box like this.
Then I checked the inspect element:
As we can compared to the one that Q2A has is this :
The "<Li />" will exceed the tag box and I don't know why I never changed any CSS layout of its class.
Furthermore this issure does not exist in the question list page as you can see here:
Does anybody can help?