Google Forms are a fast way to collect data from users when you don’t want to build an input form from scratch. A recent update means you can now use custom themes on those forms.
Google has a selection of pre-built themes on offer; you can also customise those or create your own. Elements you can alter include the form and page background, header image and the font used. For complex designs this won’t be ideal, but it helps make the standard Forms interface a little less generic.
Your Forms, your way [Google Drive Blog]