Sugestão para boxes GE-UI

gistfile1.scss

    %franja {
      position: relative;
    
      &:before {
        content: "";
        border-style: none none none solid;
        border-width: 0 0 0 80px;
        bottom: -1px;
        clear: both;
        color: #B60D3D;
        display: block;
        height: 6px;
        position: absolute;
      }
    }

    .box {
      height: 300px;
      position: relative;
      @extend %franja;
    }