Detect FireFox in HTML/CSS
@-moz-document url-prefix() {
h1 {
color: red;
}
}
<!DOCTYPE html>
<html>
<head>
<style type="text/css">
@-moz-document url-prefix() {
h1 {
color: red;
}
}
</style>
</head>
<body>
<h1>This should be red in FF</h1>
</body>
</html>