CSS variables (also called “CSS custom properties” or “cascading variables”) were first introduced in 2017. By this time, preprocessors like Sass or Less had already become the standard in web development.
When developing a WordPress theme from scratch it’s a good practice to internationalize your theme so it’s available for translation. It will allow people from all over the world to use it in whatever language they need.
Recently I was working on a new project that is developed in React. Part of my job was to translate static HTML into interactive React components. I wanted to liven up a bit the application by using animation.