Oops, I messed up with the code. I wanted to insert pure HTML/CSS.
The best way is to supply a link to the site.
Negative z-index is not wise and will get you into trouble because some browsers interpret it to be below the plane of the page. Further, it only works on positioned elements. Static elements do not have a z-index (any element that is not positioned).
<I am using z-index of -1 to put it under the logo which is above both the menu and the banner.>
A z-index: -1 puts a positioned element under the <body> which is the parent tag of all tags in your document. Only one time I have used z-index: -1 and it was a jQuery proof of concept exercise.