If you want to show the background change of #Home or #About when hovering only on a
then you can use the following:
HTML
<ul id="NavList">
<li id="Home"><a href="Second.aspx">1</a><div></div></li>
<li id="About"><a href="Second.aspx">2</a><div></div></li>
</ul>
CSS
#Home,#About {
position:relative;
width:70px;
height:50px;
}
#Home div, #About div{
position:absolute;
background: url('https://i.stack.imgur.com/2JzQz.jpg');
background-position:-20px 0px;
top:0px;
width:100%;
height:100%;
}
#Home a,#About a{
position:absolute;
top:20px;
left:20px;
z-index:100;
}
#Home a:hover+div , #About a:hover+div{
background: url('https://i.stack.imgur.com/7rx8G.jpg');
background-position:-20px 0px;
}
Got this idea from How to style the parent element when hovering a child element? .My CSS is different but using same idea.