html{
font-family:Arial, Helvetica, sans-serif;
font-size:12px;
}
#bar a{
padding:4px 6px;
background:#E0E9FE;
text-decoration:none;
font-weight:bold;
}
#bar a:hover{
color:#003366;
}
#container{
background:#E0E9FE;
padding:10px;
}
div.maintab div {
display: none
}
div.maintab div:target {
display: block
}

<div id="bar">
<a href="#tab1">Tab 1</a>
<a href="#tab2">Tab 2</a>
<a href="#tab3">Tab 3</a>
<a href="#tab4">Tab 4</a>
</div>

<div id="container">
<div class="maintab">

<div id="tab1">
Tab 1 Content
</div>

<div id="tab2">
Tab 2 Content
</div>

<div id="tab3">
Tab 3 Content
</div>

<div id="tab4">
Tab 4 Content
</div>
</div>
</div>