Hi there!
Thanks for your query!
I will convey your wish to the team!
And yes you can simply use this in the mentioned place:
.sppb-btn-primary{
width: 100%;
}
Or you can use the following code into the custom css field of the Template:
.sppb-form-builder-btn button.sppb-btn-primary{
width: 100%;
}
Note: Path towards custom CSS:
Extensions>Templates>Styles>
Click on your current default template name then choose Template Options.
Then find custom CSS within the custom code.
https://prnt.sc/pu705g
https://prnt.sc/pu70zn
Best Regards