Styling links

Hi,

Theres a requirement like, give different image links for different sites in left navigation bar. There are 5 sites to be listed out.So I have put them in a table format by hiding quick launch menu( I modified the master page).Everything is working fine. But the next requirement is ,hovering on each link / when the link is active,it should show orange color.  The following is the code of one site in master page

<table style="background:blue" ><tr id="ex1"><a href="www.google.com" ><td style="background-color:blue; width: 148px; height:40px;" valign="middle">				<label id="lblGoogle" ><img src="www.google.com" alt="" width="33" height="23" class="ms-viewselector-arrow" style="float: left"/><span class="style8">	</span><a id="imgGoogle" href="www.google.com"><span class="ms-dark"><strong><span class="style9" style="vertical-align:middle">
Google</span></strong></span></a></label></td></a>					</tr></table>

And in the css file I have written the below for hover:

#ex1:hover
{
	background-color:orange !important;
	color:white !important;
}

Instead of having ex1 as id, I have tried it with class. Even that is not working fine. Please help.

Many thanks