How to and why?
BEM – Block Element Modifier is a methodology, that helps you to achieve reusable components and code sharing in the front-end
Go to Codepen
Common pitfalls:
.block {} .block__elem1 {} .block__elem2 {} .block__elem3 {}
.block__elem1__elem2
<div class="menu__item button"></div>
<div class="menu__item button active"></div>