Forced capitalization is handled by the class is-uppercase
<h1 class="title is-size-1 is-uppercase">Get Started!</h1> = GET STARTED!
If you don't want it, you can simply remove it
<h1 class="title is-size-1">Get Started!</h1> = Get started!
Maybe you could also try using html entities to force the browser to use them? http://lilith.fisica.ufmg.br/~wag/TRANSF/codehtml.html