Write CSS rules for Firefox only

If you want to add a few CSS rules that fix issues on Firefox only, then this trick might be useful. It introduces two ways to detect Firefox:
@-moz-document url-prefix() {
h1 {
color: blue;
}
}
/* Or use `@support` */
@supports (-moz-appearance: none) {
h1 {
color: blue;
}
}
The sample code above will add the blue color to h1 on Firefox.