Reduce specificity of 'example' styles.
Add *comment heading* to 'example' block styles.
Add 'code' block styles.
Rename 'example' class to 'preview'.
Rename instances of 'example' class to 'preview'.
Add base structure for 'Buttons' section.
Style 'example' blocks. Example blocks combine preview and code blocks.
Add base styles to 'buttons' section.
Add font-family to '.typeface' styles.