Basic standalone horizontal menu Here is what I'm starting with. It is just some &lt;p&gt; tags in a &lt;div&gt; tag.

   &lt;div id='mi_control' class='radius_all'&gt;
      &lt;p id='mi_cover_l' class='menu_bottom small_dark'&gt;Arcmarks &amp;copy; &lt;/p&gt;
      &lt;p id='mi_about_l' class='menu_bottom small_dark'&gt;About&lt;/p&gt;
      &lt;p id='mi_privacy_l' class='menu_bottom small_dark'&gt;Privacy&lt;/p&gt;
      &lt;p id='mi_team_l' class='menu_bottom small_dark'&gt;Contact&lt;/p&gt;
      &lt;p id='mi_arc_l' class='menu_bottom small_dark'&gt;Developers&lt;/p&gt;
    &lt;/div&gt;


This post seems a bit unrelated as I just want to know the HTML/CSS structure for a horizontal menu.

Here is what it looks like and what I want it to look like:
Based on personal experience as well as this blog post, I'd recommend that you use an unordered list ul versus div and p, because it's a more accurate representation of the actual content you're marking up (semantic markup).

Here's a modified (div replaced with nav) snippet of the HTML from the article I linked to above:

&lt;nav class="nav"&gt;
  &lt;ul&gt;
    &lt;li class="home"&gt;&lt;a href="#"&gt;Home&lt;/a&gt;&lt;/li&gt;
    &lt;li class="tutorials"&gt;&lt;a class="active" href="#"&gt;Tutorials&lt;/a&gt;&lt;/li&gt;
    &lt;li class="about"&gt;&lt;a href="#"&gt;About&lt;/a&gt;&lt;/li&gt;
    &lt;li class="news"&gt;&lt;a href="#"&gt;Newsletter&lt;/a&gt;&lt;/li&gt;
    &lt;li class="contact"&gt;&lt;a href="#"&gt;Contact&lt;/a&gt;&lt;/li&gt;
  &lt;/ul&gt;
&lt;/nav&gt;


For the CSS to create a horizontal list, you could either use display: inline-block; or float: left; on the li items. If you need to support older browsers, like IE7, then you'll most likely want to use float. For more information on how to decide which technique to use, I'd take a look at this Stack Overflow question.