The page editor allows you to assign custom classes/styles to elements in the content area.

There are 3 custom button options for your site.  You can highlight text in your content area, select the link icon to assign a link and then choose the button class from the formats menu.  The three options are "button-small", "button-medium" and "button-large"

A div tag can be assigned the class "div-callout" and will wrap its content in the section background color.