@import url( font-awesome.min.css ) to css code example

Example 1: link font awesome html

<link
      rel="stylesheet"
      href="https://use.fontawesome.com/releases/v5.13.0/css/all.css"
      integrity="sha384-Bfad6CLCknfcloXFOyFnlgtENryhrpZCe29RTifKEixXQZ38WheV+i/6YWSzkz3V"
      crossorigin="anonymous"
    />

Example 2: fontawesome cdn

gem 'font-awesome-sass'