A tag is nested with img and cannot be clicked

Temporarily do a colleague’s file, to do the effect of the navigation bar, the navigation bar does not put text, pure pictures.

The a tag has a nested IMG, but in practice, the A link cannot be clicked, and the pointer will not change if the mouse moves over it.

After changing the CSS for a long time, setting the width and height for both A and IMG still doesn’t work.

Urgent I look for a colleague to see what the problem is, browser F12 is clearly good.

The problem was discovered when the colleague’s parent element set a Z-index.

Ten thousand in my heart… After commenting out, you can click normally.