…"float:right;margin-right:123px;height:20px;margin-top:3px;width:52px;" /></li>
The sequence <FOO /> can be interpreted in at least two different ways, depending on the DOCTYPE of the document. For HTML 4.01 Strict, the '/' terminates the tag <FOO (with an implied '>'). However, since many browsers don't interpret it this way, even in the presence of an HTML 4.01 Strict DOCTYPE, it is best to avoid it completely in pure HTML documents and reserve its use solely for those written in XHTML.
…"float:right;margin-right:123px;height:20px;margin-top:3px;width:52px;" /></li>
The attribute given above is required for an element that you've used, but you have omitted it. For instance, in most HTML and XHTML document types the "type" attribute is required on the "script" element and the "alt" attribute is required for the "img" element.
Typical values for type are
type="text/css" for <style>
and type="text/javascript" for <script>.