First off, you are using rather bad techniques for semantics.
Code:
<div class="sidehead">Member Login</div>
<div class="sidecontent">
<p>Username</p>
<p>Password</p>
</div>
<div class="sidehead">Member Login</div>
<div class="sidecontent">
<p>Username</p>
<p>Password</p>
</div>
You can use that, and then add "margin: 0 0 20px 0;" to the class "sidecontent" in your CSS.