Font-Awesome/less/_core.less

// base icon class definition
// -------------------------

.@{fa-css-prefix} {
  font-family: ~"var(--@{fa-css-prefix}-style-family, '@{fa-style-family}')";
  font-weight: ~'var(--@{fa-css-prefix}-style, @{fa-style})';
}

.@{fa-css-prefix},
.fas,
.@{fa-css-prefix}-solid,
.fass,
.@{fa-css-prefix}-sharp,
.far,
.@{fa-css-prefix}-regular,
.fab,
.@{fa-css-prefix}-brands {
  -moz-osx-font-smoothing: grayscale;
  -webkit-font-smoothing: antialiased;
  display: ~'var(--@{fa-css-prefix}-display, @{fa-display})';
  font-style: normal;
  font-variant: normal;
  text-rendering: auto;
}

.fas,
.@{fa-css-prefix}-classic,
.@{fa-css-prefix}-solid,
.far,
.@{fa-css-prefix}-regular {
  font-family: 'Font Awesome 6 Free';
}

.fab,
.@{fa-css-prefix}-brands {
  font-family: 'Font Awesome 6 Brands';
}