The level-2 drop-down menu is hidden, and CSS setting of Z-index does not work in IE. Solution

Jquery makes a second-level menu with a mouse and adds an animation effect. Firefox is perfectly rendered. Some drop-down menus under IE will be covered by the following webpage content, such as IFRAME, Div, and drop-down box, input box, etc.

The result of setting the Z-index in IE does not have any effect, and the jquery plug-in bgiframe is integrated. The result can only solve the selection box under IE6. I was dizzy by the Z-index bug of IE. I have done it several times. Note:

1. Pay attention to SettingsParent ElementZ-index (Because Z-index has inheritance, stacking context, stacking level)
2. the position: relative/absolute must be specified.
3. If the value of Z-index is negative, different browsers may behave differently. Google does not need a negative value.

I hope it will be useful to those who are troubled by IE Z-index.