main class="hero is-fullheight center"> code example
Example: bulma fullheight
<section class="hero is-success is-fullheight">
<div class="hero-body">
<div class="container">
<h1 class="title">
Fullheight title
</h1>
<h2 class="subtitle">
Fullheight subtitle
</h2>
</div>
</div>
</section>