Why z-index is not working?

Question

I have this HTML code:

    

        
Title goes here
    

&         


        

Answer 1

Just manually set the #right-block position :

#right-block {
    position: relative;
    float: right;
    background-color: blue;
    height: 50px;
    z-index: 5;
}

z-index only woks on absolute|relative|fixed positioned elements, and the default value is for position is static.