Updated to Drupal 8.6.4, which is PHP 7.3 friendly. Also updated HTMLaw library....

[yaffs-website] / web / modules / contrib / layout_plugin / tests / modules / layout_test / css / layout-test-2col.css

.layout-example-2col .region-left {
  float: left;
  width: 50%;
}
* html .layout-example-2col .region-left {
  width: 49.9%;
}

.layout-example-2col .region-right {
  float: left;
  width: 50%;
}
* html .layout-example-2col .region-right {
  width: 49.9%;
}