So the LI elements you can give them a margin-bottom: 2em;
property.
Personally i would write my HTML like this, you don’t need the DIV:
<ul class="button-list">
<li><a class="ktg-button" href="url">Button label</a></li>
<li><a class="ktg-button" href="url">Button label</a></li>
<li><a class="ktg-button" href="url">Button label</a></li>
</ul>
And then add this CSS:
ul.button-list {
list-style: none;
display: inline;
margin: 0;
}
ul.button-list > li {
display: inline-block;
margin-bottom 2em;
}