Conditionally shades block level elements (No Compass)

block-x-ray-nocompass.scss

$show-blocks: true; // Show Block Shading

// Shades all block level elements if show-blocks is true
@if $show-blocks == true {
  address, article, aside, blockquote,
  center, dd, details, dir, div, dl,
  dt, fieldset, figcaption, figure,
  footer, form, frameset, h1, h2, h3,
  h4, h5, h6, header, hgroup, hr,
  isindex, menu, nav, noframes,
  noscript, ol, p, pre, section,
  summary, ul{
    background: rgba(0,0,0,0.2);
  }
}