#menu { width: 750px; height: 22px; list-style: none; padding: 0; }
#menu li { width: 25%; height: 100%; text-align: center;
            margin: 0px; padding: 0px; float: left }
#menu a { display: block; margin: 0px 1%; height: 100%;
           background: #999; color: white; text-decoration: none; }
#menu a:hover { color: gold; }


<ul id="menu">
   <li><a href="1.htm">page 1</a></li>
   <li><a href="2.htm">page 2</a></li>
   <li><a href="3.htm">page 3</a></li>
   <li><a href="4.htm">page 4</a></li>
</ul>