[destus]

Rostik,
как вариант...

<style>
        .post{
            width: 500px;
            height: 40px;
            background: #666;
            margin-top: 10px;
            transition: height .5s ease-in;
        }
        .post.active{
            height: 140px;
        }
</style>
<div class="post"></div>
    <div class="post"></div>
    <div class="post"></div>
    <script>
		[].forEach.call(document.querySelectorAll('.post'), function(div){
			div.addEventListener('click', function(){
				this.classList.toggle('active');
			})
		})
    </script>