Super

<h1 class="c-heading u-super">Super</h1> 

Extra Large

<h1 class="c-heading u-xlarge">Extra Large</h1> 

Large

<h1 class="c-heading u-large">Large</h1> 

Medium

<h1 class="c-heading u-medium">Medium</h1> 

Small

<h1 class="c-heading u-small">Small</h1> 

Extra Small

<h1 class="c-heading u-xsmall">Extra Small</h1>