<ul>
<ul>
<li><img src="http://placekitten.com/50/50" /></li>
<li><img src="http://placekitten.com/50/100" /></li>
<li><img src="http://placekitten.com/50/50" /></li>
<li><img src="http://placekitten.com/50/100" /></li>
<li><img src="http://placekitten.com/50/50" /></li>
<li><img src="http://placekitten.com/50/100" /></li>
<li><img src="http://placekitten.com/50/50" /></li>
<li><img src="http://placekitten.com/50/100" /></li>
</ul>
ul {
ul {
columns: 50px;
columns: 50px;
columns: 50px;
}