Bulma class: .is-size-*

<span class="is-size-1">Text size 1</span>
<span class="is-size-2">Text size 2</span>
<span class="is-size-3">Text size 3</span>
<span class="is-size-4">Text size 4</span>
<span class="is-size-5">Text size 5</span>
<span class="is-size-6">Text size 6</span>