How to make links clickable with negative z-index?

Question

I am using drop-down menu in my header for notification, but when drop down opens all the div's behind that are visible then I gave z-index to all the divs but the links on those div's are not clickable now!

drop-down div CSS:

.drop-down{
   overflow:scroll;
   overflow-x:hidden;
}

and the div's behind it are

#main-div{
   z-index:-1;
   position:absolute;
}

Answer 1

I guess that the negative z-index places the links underneath the body.

Use a positive z-index, for example 10 on the element that should be at the back and 20 on the element that should be in front.