In CSS, em and rem represent relative units that display the scalable and responsive results.
em: It is relative to the font size of the parent. For example, if a parent font size is 20px, then2emwill equal 40px.rem: It’s relative to root element font size, usually<html>. For example, if root font size is 16px, then1remequals 16px.
Related
CSS Combinators
A combinator is a sign that explains the relationship between selectors.
CSS Selectors
CSS selectors are used to “find” (or select) the HTML elements you want to style.
Minify CSS and JavaScript
发布博客时，压缩CSS和JavaScript文件的大小，能提升网页的加载速度，这里介绍使用cssnano和Terser工具来压缩。