Targeting only Firefox with CSS

Question

Using conditional comments it is easy to target Internet Explorer with browser-specific CSS rules:

<!--[if IE 6]>
...include IE6-specific stylesheet here...
<![endif]-->

Sometimes it is the Gecko engine (Firefox) that misbehaves. What would be best way to target only Firefox with your CSS rules and not a single other browser? That is, not only should Internet Explorer ignore the Firefox-only rules, but also WebKit and Opera should.

Note: I'm looking for a 'clean' solution. Using a JavaScript browser sniffer to add a 'firefox' class to my HTML does not qualify as clean in my opinion. I would rather like to see something that depends on browser capabilities, much like conditional comments are only 'special' to IE…

Might want to look at some similar questions and thier related answers... stackoverflow.com/questions/738831/… — AnonJr
– AnonJr, Commented Jun 4, 2009 at 20:21
is there any way to target firefox on a windows machine vs a mac? — Kegan Quimby
– Kegan Quimby, Commented May 8, 2012 at 19:09
@KeganQuimby If one's interest is for userChrome.css and userContent.css, the answer is yes! See stackoverflow.com/questions/79104161/… — Amazon Dies In Darkness
– Amazon Dies In Darkness, Commented Oct 19, 2024 at 8:46

Adam Katz · Accepted Answer · 2025-01-16 19:03:32Z

1456

This solution does not rely on JavaScript being turned on.

@-moz-document url-prefix() {
  h1 {
    color: red;
  }
}

<h1>This should be red in FF</h1>

This is based on a Mozilla-specific CSS extension. Like most of these, it is deprecated. However, this extension's deprecation has an exception specifically for browser detection. The Firefox note in @document § browser compatibility states that Firefox 61+ "only supports an empty url-prefix() value, which is supported due to its use in Firefox browser detection. Still supported in user stylesheets."

For more information about this specific CSS extension, see What does @-moz-document url-prefix() do?

edited Jan 16 at 19:03

Adam Katz

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answered Jun 4, 2009 at 22:43

Ionuț G. Stan

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14 Comments

Matt Over a year ago

What exactly does the url-prefix() mean after the "@-moz-document" ? just curious.

Ionuț G. Stan Over a year ago

@Matt, that's a way to filter the websites on which that CSS is applied. Another option is to use the domain() filter. For example @-moz-document domain(google.com) {...} will apply the enclosed CSS rules only on the google.com domain.

JD Isaacks Over a year ago

I like how you don't have to create an entirely new CSS document for this like you do for IE.

Dylan Over a year ago

@JohnIsaacks You don't need a separate stylesheet for the IE conditional comments. They can be inline. Whether you want to do it that way is another question.

Jordan Gray Over a year ago

It's worth noting that this workaround no longer works as of Firefox 59, released March 2018: bugzilla.mozilla.org/show_bug.cgi?id=1035091

|

laaposto · Accepted Answer · 2017-11-29 10:22:19Z

208

Updated(from @Antoine comment)

You can use @supports

@supports (-moz-appearance:none) {
    h1 { color:red; } 
}

<h1>This should be red in FF</h1>

3 Comments

Alastair Hodgson Over a year ago

This is a much nicer solution than @-moz-document url-prefix() example, it also plays nice with SCSS parser whereas the other one didn't.

izogfif Over a year ago

Note: sometimes you need to add extra spaces around brackets: @supports ( -moz-appearance:none ). Otherwise Chrome chokes on this.

Adam Katz Jan 16 at 18:46

This is, unfortunately, a moving target. Refer to this list of Mozilla-only properties. You want something in that first section and without a trash can icon. At the moment, orient looks among the best, as in @supports not ( -moz-orient: block ) { .firefox-only { display: none } }, but the accepted @-moz-document solution here is actually ~officially supported

Barney · Accepted Answer · 2015-06-16 08:33:14Z

85

Here is how to tackle three different browsers: IE, FF and Chrome

<style type='text/css'>
/*This will work for chrome */
#categoryBackNextButtons
{
    width:490px;
}
/*This will work for firefox*/
@-moz-document url-prefix() {
    #categoryBackNextButtons{
        width:486px;
    }
}
</style>
<!--[if IE]>
<style type='text/css'>
/*This will work for IE*/
#categoryBackNextButtons
{
    width:486px;
}
</style>
<![endif]-->

edited Jun 16, 2015 at 8:33

Barney

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answered Jan 21, 2011 at 9:33

Waqas Ali

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4 Comments

Muhd Over a year ago

If I understand this correctly, the top one isn't chrome, but just specifies the default behavior which you override for Firefox and IE.

SpaceBeers Over a year ago

Very useful. As an ex Firefox lover, I'm gutted that I have to do Firefox specific hacks like this but so long as it works I can live with it.

Biepbot Von Stirling Over a year ago

The suggestion for IE detection does not work if you want to add it into a .css file. You can include stylesheets with it that way in HTML though. If you want to have IE CSS in a CSS file, I recommend looking at here: keithclark.co.uk/articles/…

MoxJet Sep 10 at 20:33

Note that you must use a higher specificity selector inside @-moz-document or else it won't work in some situations

Hbirjand · Accepted Answer · 2014-08-26 10:34:35Z

16

Here is some browser hacks for targeting only the Firefox browser,

Using selector hacks.

_:-moz-tree-row(hover), .selector {}

JavaScript Hacks

var isFF = !!window.sidebar;

var isFF = 'MozAppearance' in document.documentElement.style;

var isFF = !!navigator.userAgent.match(/firefox/i);

Media Query Hacks

This is gonna work on, Firefox 3.6 and Later

@media screen and (-moz-images-in-menus:0) {}

If you need more information,Please visit browserhacks

edited Aug 26, 2014 at 10:34

answered Aug 20, 2014 at 5:45

Hbirjand

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4 Comments

red-o-alf Over a year ago

Could you elaborate a bit more on "using selector hacks" and on how the example you provided specifically works? Thanks.

red-o-alf Over a year ago

Alright got it myself: basically what it does is hiding the second selector to other browsers which don't understand the first one. In this case only Mozilla understands _:moz-tree-row(hover) so it will be the only one to be able to process the .selector{} coming after. This specifical hacks currently works on all version of Firefox, check browserhacks.com for more on this.

Dan Randolph Over a year ago

I used the Media Query Hack: \@media screen and (-moz-images-in-menus:0) {} This goes nicely with \@media screen and (-webkit-min-device-pixel-ratio:0) and Visual Studio does not throw a warning using it.

jonathanKingston Over a year ago

Please note -moz-images-in-menus:0 has been removed in Firefox 52 - bugzilla.mozilla.org/show_bug.cgi?id=1302157

Ionuț G. Stan · Accepted Answer · 2009-06-04 21:16:16Z

First of all, a disclaimer. I don't really advocate for the solution I present below. The only browser specific CSS I write is for IE (especially IE6), although I wish it wasn't the case.

Now, the solution. You asked it to be elegant so I don't know how elegant is it but it's sure going to target Gecko platforms only.

The trick is only working when JavaScript is enabled and makes use of Mozilla bindings (XBL), which are heavily used internally in Firefox and all other Gecko-based products. For a comparison, this is like the behavior CSS property in IE, but much more powerful.

Three files are involved in my solution:

ff.html: the file to style
ff.xml: the file containg the Gecko bindings
ff.css: Firefox specific styling

ff.html

<!DOCTYPE html>

<html>
<head>
<style type="text/css">
body {
 -moz-binding: url(ff.xml#load-mozilla-css);
}
</style>
</head>
<body>

<h1>This should be red in FF</h1>

</body>
</html>

ff.xml

<?xml version="1.0"?>

<bindings xmlns="http://www.mozilla.org/xbl">
    <binding id="load-mozilla-css">
        <implementation>
            <constructor>
            <![CDATA[
                var link = document.createElement("link");
                    link.setAttribute("rel", "stylesheet");
                    link.setAttribute("type", "text/css");
                    link.setAttribute("href", "ff.css");

                document.getElementsByTagName("head")[0]
                        .appendChild(link);
            ]]>
            </constructor>
        </implementation>
    </binding>
</bindings>

ff.css

h1 {
 color: red;
}

Update: The above solution is not that good. It would be better if instead of appending a new LINK element it will add that "firefox" class on the BODY element. And it's possible, just by replacing the above JS with the following:

this.className += " firefox";

The solution is inspired by Dean Edwards' moz-behaviors.

Rayjax · Accepted Answer · 2015-01-13 16:57:57Z

Using -engine specific rules ensures effective browser targeting.

<style type="text/css">

    //Other browsers
    color : black;


    //Webkit (Chrome, Safari)
    @media screen and (-webkit-min-device-pixel-ratio:0) { 
        color:green;
    }

    //Firefox
    @media screen and (-moz-images-in-menus:0) {
        color:orange;
    }
</style>

//Internet Explorer
<!--[if IE]>
     <style type='text/css'>
        color:blue;
    </style>
<![endif]-->

BoltClock · Accepted Answer · 2017-12-14 04:31:38Z

Now that Firefox Quantum 57 is out with substantial — and potentially breaking — improvements to Gecko collectively known as Stylo or Quantum CSS, you may find yourself in a situation where you have to distinguish between legacy versions of Firefox and Firefox Quantum.

From my answer here:

You can use @supports with a calc(0s) expression in conjunction with @-moz-document to test for Stylo — Gecko does not support time values in calc() expressions but Stylo does:
@-moz-document url-prefix() {
  @supports (animation: calc(0s)) {
    /* Stylo */
  }
}
Here's a proof-of-concept:
body::before {
  content: 'Not Fx';
}

@-moz-document url-prefix() {
  body::before {
    content: 'Fx legacy';
  }

  @supports (animation: calc(0s)) {
    body::before {
      content: 'Fx Quantum';
    }
  }
}
Targeting legacy versions of Firefox is a little tricky — if you're only interested in versions that support @supports, which is Fx 22 and up, @supports not (animation: calc(0s)) is all you need:
@-moz-document url-prefix() {
  @supports not (animation: calc(0s)) {
    /* Gecko */
  }
}
... but if you need to support even older versions, you'll need to make use of the cascade, as demonstrated in the proof-of-concept above.

Anzil khaN · Accepted Answer · 2018-03-16 07:40:40Z

8

A variation on your idea is to have a server-side USER-AGENT detector that will figure out what style sheet to attach to the page. This way you can have a firefox.css, ie.css, opera.css, etc.

You can accomplish a similar thing in Javascript itself, although you may not regard it as clean.

I have done a similar thing by having a default.css which includes all common styles and then specific style sheets are added to override, or enhance the defaults.

edited Mar 16, 2018 at 7:40

Anzil khaN

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answered Jun 4, 2009 at 20:26

Kekoa

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2 Comments

avdgaag Over a year ago

That does some like a nice and stable approach — thanks — although it still depends on browser sniffing. I'd rather use something that depends on capability, like a Gecko-only CSS rule or something. I do use the same basic approach: default styles and browser-specific add-ons.

Lèse majesté Over a year ago

@avdaag: Capability detection is preferred in most cases, but when you're trying to inject a hack to "fix" a specific rendering engine's bug, then targeting the user agent is, in theory, the optimal solution. You're not discriminating against unknown browsers; and the user-agent field is supposed to tell you what rendering engine the browser is using, so even if a rare Gecko browser comes along, it'll still be given the fix. That said, a lot of browsers now fake their user-agent strings due to inappropriate use of browser-detection. So in practice it might not work out so well.

Time Killer · Accepted Answer · 2021-05-31 14:26:32Z

4

with -moz prefix

div:-moz-read-only {
  background: green;
}

textarea:-moz-read-write {
  background: green;
}

:-moz-any(div#foo) div.bar {
  background: green;
}

li:-moz-first-node, li:-moz-last-node {
  background: green;
}

edited May 31, 2021 at 14:26

answered May 30, 2021 at 16:53

Time Killer

85410 silver badges26 bronze badges

Comments

Stokely · Accepted Answer · 2022-08-26 05:38:55Z

How to Apply CSS to Only Firefox

This solution below offers you decent Firefox-only CSS support in a wider range of Firefox browser versions...

@supports (-moz-appearance:button) and (contain:paint) {

  body {
    background: red;
  }

}

-moz-appearance:button was supported in Mozilla/Firefox as early as 2006. But the @supports rule was not supported till 2019 so that would be the earliest Firefox browser supporting this rule. contain:paint excludes Safari browsers from the rule. Internet Explorer and early Trident Edge browsers do not support @supports so also excluded from seeing the CSS rule. No known Chrome browser should support -moz-appearance:button, so excluded.

As always, all my CSS solutions are 100% JavaScript-free :)

Jerod Venema · Accepted Answer · 2009-06-04 20:22:19Z

3

The only way to do this is via various CSS hacks, which will make your page much more likely to fail on the next browser updates. If anything, it will be LESS safe than using a js-browser sniffer.

answered Jun 4, 2009 at 20:22

Jerod Venema

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Comments

NVRM · Accepted Answer · 2021-12-06 18:24:23Z

2

CSS support can be used from JavaScript.

if (CSS.supports("( -moz-user-select:unset )")) {
    console.log("FIREFOX!!!")
}

https://developer.mozilla.org/en-US/docs/Web/CSS/Mozilla_Extensions

edited Dec 6, 2021 at 18:24

answered Mar 16, 2019 at 16:52

NVRM

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Comments

atazmin · Accepted Answer · 2023-06-27 18:44:19Z

2

I use this with Google Web Designer to target Firefox

@supports (-moz-appearance:none) {
  .class-name {
        
  }
}

answered Jun 27, 2023 at 18:44

atazmin

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Comments

Kailas · Accepted Answer · 2017-11-29 09:46:43Z

1

The following code tends to throw Style lint warnings:

@-moz-document url-prefix() {
    h1 {
        color: red;
    }
}

Instead using

@-moz-document url-prefix('') {
    h1 {
        color: red;
    }
}

Helped me out! Got the solution for style lint warning from here

answered Nov 29, 2017 at 9:46

Kailas

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