These utilities extend the basscss-btn styles to modify button sizes.
To change the line-height and padding but leave the font-size the same, use button size extensions.
<button type="button" class="btn btn-big btn-primary mb1">Burgers</button>
<button type="button" class="btn btn-primary mb1">Fries</button>
<button type="button" class="btn btn-narrow btn-primary mb1">Onion Rings</button>
<button type="button" class="btn btn-small btn-primary mb1">Shakes</button>