Responsive style

So I have made a simple form that I have styled.

But I have noticed that on the mobile version that some of the text styles are different. 

And I can't find a way to adjust them in the designer. 

Are you referring to this, when you say that the text styles are different on mobile?

You can change that by Injecting Custom CSS. To do that inside of your Form Builder select Setup & Embed tab, then click on Preferences, then select Form Styles tab and inside of Inject Custom CSS field at the bottom of existing code paste this code:

@media screen and (min-width: 10px) and (max-width: 480px){

.form-header{

font-weight : bold!important;

}}

@media screen and (min-width: 480px) and (max-width: 720px){

.form-header{

font-weight : bold!important;

}}

After adding this code your form will look like this.

Hope this will help. Let us know if you need further assistance.