Although Google Sites is very simple to learn and use, that simplicity comes at a price – limited customization. Until very recently, you used the Themes panel to choose the look of your site. You could choose a color option and font for the entire site, but that’s it.
No more! 
Recall that when working with text you can choose from Normal text, Title, Heading, Subheading, and small to format your text boxes. That has not changed.
What has changed is that you can now choose text options just like you can in any other Google app.
This brings Google Sites inline with other web design tools and makes it much more customizable.
This eliminates many of the criticisms I have with Sites and now I wholeheartedly recommend it for most people’s needs. I am thankful that Google listens to feedback from its users.