Twitter-bootstrap-3 | Thumbnail Centering? - center

Question

Hey Guys!
I'm currently working on a website using twitter bootstrap 3 but I've got some issues. I'm trying to center the 3 thumbnails I've got. The text is centered, image is centered but I can't seem to get the thumbnails centered. Here is my code:
<div class="row">
<div class="col-sm-6 col-md-3">
<div class="thumbnail">
<img src="img/test.png">
<div class="caption">
<p>test</p>
</div>
</div>
</div>
<div class="col-sm-6 col-md-3">
<div class="thumbnail">
<img src="img/test.png">
<div class="caption">
<p>test</p>
</div>
</div>
</div>
<div class="col-sm-6 col-md-3">
<div class="thumbnail">
<img src="img/test.png>
<div class="caption">
<p>test</p>
</div>
</div>
</div>
CSS:
.thumbnail {
background-color: #cecece;
border: 1px solid #666;
text-align:center;
}

Answer 1

to center your content on the page, wrap the row in a containter ()
Notice that Bootstrap uses a 12 column grid. To fill your row with tree thumbs for the medium (md) grid, consider to use the col-md-4 class (3 x 4 = 12) class for your columns. ON the small (sm) grid you now have 3 columns of 50% by using three times the col-sm-6 class. Consider to use only one class, only the col-md-4 class will give you 3 columns for a screen width of 992px or wider and only the col-sm-4 class does the same but for screen widths of 768px and wider. Below the 992 or 768 the columns will stack.
The text can be centered by applying the text-center class, also see http://getbootstrap.com/css/#type-alignment
Also see: http://www.bootply.com/WAFUzlJs8s