The dropdown menu of my blog will get behind the look slider around the primary page.

How do you cure it therefore the the dropdown menu isn't covered?

For the information, the dropdown menu doesn't need any javascript and exclusively is dependent upon css. Thanks.

This can repair it:

#menu-wrapper {
    position: relative;
    z-index: 40;

To exhibit it works:

Set position:relative and z-index:9999 around the #menu-wrapper rule