chore(css) separate selectors and declarations by new lines

This PR follows the Google CSS guidelines rule to start a [new line for each selector and declaration](https://google-styleguide.googlecode.com/svn/trunk/htmlcssguide.xml?showone=Selector_and_Declaration_Separation#Selector_and_Declaration_Separation). Separated selectors and declarations by new lines for readability and consistency in the two CSS files.