This is another solution using clickable articles (can of course be changed to anything).
http://jsfiddle.net/SqJ53/2/
Edit: If you want to use CSS animation, you must use MAX-HEIGHT instead of HEIGHT
Javascript
$(".container article").click(function() {
        $(this).toggleClass("expand");
})
CSS
.container {
    position: relative;
    width: 900px;
    height: auto;
}
.container article {
    position: relative;
    border: 1px solid #999;
    height: auto;
    max-height: 105px;
    overflow: hidden;
    -webkit-transition: all .5s ease-in-out;
    -moz-transition: all .5s ease-in-out;
    transition: all .5s ease-in-out; 
}
.container article:hover {
    background: #dadada;
}
.container article.expand {
    max-height: 900px;
}
HTML
<div class="container">
    <article class="posts-by-cat_article-222">
        <h3><a href="http://google.se">Section 1</a></h3>
        <p>This is my super long content, just check me out.</p>
        <p>This is my super long content, just check me out.</p>
        <p>This is my super long content, just check me out.</p>
        <p>This is my super long content, just check me out.</p>
    </article>
    <article class="posts-by-cat_article-222">
        <h3><a href="http://google.se">Section 2</a></h3>
        <p>This is my super long content, just check me out.</p>
        <p>This is my super long content, just check me out.</p>
        <p>This is my super long content, just check me out.</p>
        <p>This is my super long content, just check me out.</p>
    </article>
</div>