Bootstrap V4 introduced spacing utility classes (like a class m-t-1 to get margin-top: 1rem!important), which inspired others to create this great universal.css project: https://github.com/marmelab/universal.css
Is this a joke?
Of course it's a joke. Use semantic CSS class names. styleElement.appendChild(document.createTextNode(styleContent.replace(/;/g, ' !important;')));