I find a tutorial about bootstrap grid, but it was written in bootstrap1.x. Now I want to use bootstrap3 to achieve the same effect. The doc says using .img-thumbnail instead of .media-grid, but it seems still not work. What I want is something like this:
The 1.x version is:
<ul class="media-grid">
<li>
<a href="#">
<img src="http://placehold.it/290x200" />
</a>
</li>
<li>
<a href="#">
<img src="http://placehold.it/290x200" />
</a>
</li>
<li>
<a href="#">
<img src="http://placehold.it/290x200" />
</a>
</li>
<!-- row of 4 thumbnails -->
<li>
<a href="#">
<img src="http://placehold.it/210x140" />
</a>
</li>
<li>
<a href="#">
<img src="http://placehold.it/210x140" />
</a>
</li>
<li>
<a href="#">
<img src="http://placehold.it/210x140" />
</a>
</li>
<li>
<a href="#">
<img src="http://placehold.it/210x140" />
</a>
</li>
</ul><!-- end media-grid -->