There was actually an extra </div>, not an open one...
And the Blog service just does not insert proper xhtml...
Take a look at the code I actually edit:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title><$BlogPageTitle$></title>
<$BlogMetaData$>
<style type="text/css">
body
{
color:rgb(225,225,225);
background-color:rgb(0,0,0);
margin-left:auto;
margin-right:auto;
text-align:center;
}
div.blog
{
border-style:solid;
border-color:white;
float:center;
margin-left:15%;
margin-right:10px;
margin-top:5%;
padding:10px;
width:600px;
}
div.sidebar
{
float:right;
margin-top:5%;
margin-right:10px;
margin-left:10px;
padding:10px;
border:1px;
border-color:white;
width:200px;
height:600px;
border-style:solid;
border-width:thin;
border-color:white;
}
</style>
</head>
<body>
<div class="sidebar">
This is the Sidebar! Look at it! Marvel at it! Leave comments about it! It is the almighty Sidebar!
</div>
<div class="blog"
<ItemPage><a href="<$BlogURL$>"></ItemPage>
<$BlogTitle$>
<ItemPage></a></ItemPage>
<Blogger>
<BlogDateHeader>
<h2 class="date-header"><$BlogDateHeaderDate$></h2>
</BlogDateHeader>
<!-- Begin .post -->
<div class="post"><a name="<$BlogItemNumber$>"></a>
<BlogItemTitle>
<h3 class="post-title">
<BlogItemUrl><a href="<$BlogItemUrl$>" title="external link"></BlogItemUrl>
<$BlogItemTitle$>
<BlogItemUrl></a></BlogItemUrl>
</h3>
</BlogItemTitle>
<div class="post-body">
<p><$BlogItemBody$></p>
</div>
<p class="post-footer">posted by <$BlogItemAuthorNickname$> at
<a href="<$BlogItemPermalinkUrl$>" title="permanent link"><$BlogItemDateTime$></a>
<MainOrArchivePage><BlogItemCommentsEnabled> |
<a class="comment-link" href="<$BlogItemCommentCreate$>"<$BlogItemCommentFormOnclick$>><$BlogItemCommentCount$> comments</a>
</BlogItemCommentsEnabled></MainOrArchivePage> <$BlogItemControl$></p>
</div>
<!-- End .post -->
<!-- Begin #comments -->
<ItemPage>
<div id="comments">
<BlogItemCommentsEnabled><a name="comments"></a>
<h4><$BlogItemCommentCount$> Comments:</h4>
<ul>
<BlogItemComments>
<li id="c<$BlogCommentNumber$>"><a name="c<$BlogCommentNumber$>"></a>
<div class="comment-body">
<p><$BlogCommentBody$></p>
</div>
<p class="comment-data">By <$BlogCommentAuthor$>, at <a href="#c<$BlogCommentNumber$>" title="comment permalink"><$BlogCommentDateTime$></a>
<$BlogCommentDeleteIcon$></p>
</li>
</BlogItemComments>
</ul>
<p class="comment-data">
<$BlogItemCreate$>
<br /><br />
</BlogItemCommentsEnabled>
<a href="<$BlogURL$>"><< Home</a>
</p>
</div>
</ItemPage>
<!-- End #comments -->
</Blogger>
<hr />
</div><!-- End #main-content -->
<!-- End #content -->
</body>
</html>