strapi/packages/strapi-admin/files/public/app/styles/main.scss

// Import variables
@import "variables/variables";
@import "base/fonts";

:global {
  // Expose libs styles
  @import "libs/bootstrap/bootstrap";
  @import "libs/fontawesome/fontawesome";

  // Expose base styles
  @import "base/helpers";
  @import "base/animations";

  // Set the global font-size in order
  // to be able to have `1rem = 10px`.
  html {
    font-size: 62.5%;
  }
}