Well maybe it is. But not in our case. Let me explain.
Let's get right to the point: how often you think "ah, paying 15$ for udemy or coursera course is not worth it"?
Since many of you wanted to know more about the specifics on PWA and INSTANT APPS, here is a quick review on the two, we will look at the 3 basic componential parts.
If you write a lot of CSS, preprocessor like SASS can significantly ease the amount of your work and your stress levels. Things like Sass, Less, Stylus or PostCSS make your CSS files more readable and improve maintainability. Thanks to variables and functions the code will become cleaner, better structured and as a result help developers to work faster and make less errors.
(the fastest and easiest way is to use their official 'out of the box' solution)
If you have ever asked those questions yourself. Here is a quick recipe how to not get confused.
Here is a list of some the nice effects, interesting ideas and useful components.
Below is a list of CSS interview questions that you are very likely to face when applying for a front end position.