Review layout CSS and markup

Problem/Motivation

Five layouts were being added with rudimentary CSS and markup:

• layout_onecol
• layout_twocol
• layout_twocol_bricks
• layout_threecol_25_50_25
• layout_threecol_33_34_33

Additionally the generic layout.html.twig was added with no CSS.

Proposed resolution

Review the CSS and markup

Remaining tasks

• Review the CSS for each layout
• Review the templates for each layout
  • Ensure templates have similar indentation
  • Check that layouts with top and bottom regions have logic to hide them if there is no content

User interface changes

N/A

API changes

N/A

Data model changes

N/A