Prevent scroll when user is not in focus mode

codesyntax.less

// Before the user is in 'focus' mode.
.cw-code, .cw-prose {
  &:after {
    content: " ";
    display: block;
    position: absolute;
    width: 100%;
    height: 100%;
    top:0px;
    left:0px;
    background:rgba(0,0,0,0.25);
    text-align: center;
    padding-top: 30%;
    color: @offWhite;
    overflow-y: hidden;
  }
}

// Allow scroll once we are in 'focus mode'
&.focus {
  .cw-code, .cw-prose {
    &:after {
      display:none;
    }
  }
  .cw-code {
    &.resizing::after {
      content: "\2190  resizing \2192";
      display: block;
      position: absolute;
      width: 100%;
      height: 100%;
      top:0px;
      left:0px;
      background:rgba(0,0,0,0.75);
      text-align: center;
      padding-top: 30%;
      color: @offWhite;
      z-index: @zindex-top;
    }
  }
}