src/scss/bootstrap-4.0.0-alpha.6/scss/mixins/_screen-reader.scss

   1 // Only display content to screen readers
   2 //
   3 // See: http://a11yproject.com/posts/how-to-hide-content
   4
   5 @mixin sr-only {
   6   position: absolute;
   7   width: 1px;
   8   height: 1px;
   9   padding: 0;
  10   margin: -1px;
  11   overflow: hidden;
  12   clip: rect(0,0,0,0);
  13   border: 0;
  14 }
  15
  16 // Use in conjunction with .sr-only to only display content when it's focused.
  17 //
  18 // Useful for "Skip to main content" links; see https://www.w3.org/TR/2013/NOTE-WCAG20-TECHS-20130905/G1
  19 //
  20 // Credit: HTML5 Boilerplate
  21
  22 @mixin sr-only-focusable {
  23   &:active,
  24   &:focus {
  25     position: static;
  26     width: auto;
  27     height: auto;
  28     margin: 0;
  29     overflow: visible;
  30     clip: auto;
  31   }
  32 }