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Missing CSS rules in Firefox Developer's inspector

lebrun
lebrun
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My inspector doesn't display CSS rules for any given site. I've had this issue for two+ months, multiple FF versions. The only rules I can see are for containers above body, I.E. html. The CSS are being applied just fine, only the rules panel in the inspector fails.

Using the Safe Mode without Add-ons works makes the rules come back. Regular mode with every Add-On disabled doesn't.

I want to avoid reinstalling Firefox if possible. It's a pain to re-setup everything, and other people have experienced the same issue, multiple times even. Sounds like an introduced bug, not a random installation hiccup.

It's similar to these issues, except it happens with any site for me: https://support.mozilla.org/en-US/questions/1135537 https://support.mozilla.org/en-US/questions/1110326

Any ideas?

My inspector doesn't display CSS rules for any given site. I've had this issue for two+ months, multiple FF versions. The only rules I can see are for containers above body, I.E. html. The CSS are being applied just fine, only the rules panel in the inspector fails. Using the Safe Mode without Add-ons works makes the rules come back. Regular mode with every Add-On disabled doesn't. I want to avoid reinstalling Firefox if possible. It's a pain to re-setup everything, and other people have experienced the same issue, multiple times even. Sounds like an introduced bug, not a random installation hiccup. It's similar to these issues, except it happens with any site for me: https://support.mozilla.org/en-US/questions/1135537 https://support.mozilla.org/en-US/questions/1110326 Any ideas?
Attached screenshots

Modified by lebrun

Chosen solution

Some of the other headline effects of Firefox's Safe Mode are:

  • disables hardware acceleration -- based on your graphics information (thank you for sharing), it's already disabled in regular mode
  • disables userChrome.css and userContent.css -- do you use either of these customization files in your current Firefox profile?
  • disables JavaScript compilers -- hard to see how this could be relevant

http://kb.mozillazine.org/Safe_Mode

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All Replies (3)

jscher2000 - Support Volunteer
jscher2000 - Support Volunteer
  • Top 25 Contributor
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Chosen Solution

Some of the other headline effects of Firefox's Safe Mode are:

  • disables hardware acceleration -- based on your graphics information (thank you for sharing), it's already disabled in regular mode
  • disables userChrome.css and userContent.css -- do you use either of these customization files in your current Firefox profile?
  • disables JavaScript compilers -- hard to see how this could be relevant

http://kb.mozillazine.org/Safe_Mode

lebrun
lebrun Question owner
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That's it. jscher, you're a genius and I'm very dumb, hahah!

It was caused by userContent.css. It had a valid font-family rule for body tags to cover sites that screwed up their fonts. That explains why only rules for body and its children where missing.

It seems Firefox applies those rules without an assigned domain just fine, but breaks the rules panel for the affected elements in the process. I just tested with input it tags and as able to reproduce the issue.

I think rules without @-moz-document domain() are semantically correct—you'll find tons of tutorials on userContent doing that, MozillaZine included—meaning it's likely a bug.

Modified by lebrun

jscher2000 - Support Volunteer
jscher2000 - Support Volunteer
  • Top 25 Contributor
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Hmm, maybe file a bug on that since the panel should still work even when you've injected font rules using userContent.css.

You might create a new profile to see how compact a test case you can create (the easier it is for the developers to replicate, the faster they can assess the problem).