Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

Use a compressed image type like PNG or JPG to save the screenshot.

Make sure that you haven't enabled a High Contrast theme in the Windows/Mac Accessibility settings.

• http://support.apple.com/kb/HT1343#odd10

See also:

• http://kb.mozillazine.org/Website_colors_are_wrong
• http://kb.mozillazine.org/Websites_look_wrong

Hello,

Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

Thank you.

Starting in Safe Mode did not help. The CSS is still not showing.

I have tried all of the suggestions you listed. High Contrast is not enabled, it's set to allow pages to choose own colors, etc. I also made sure the CSS was validated for W3C. I did not have this problem in ver 22, it happened when a number of us updated to ver 23. We are seeing it on all computers that updated to ver 23. It is happening on both Mac and PC.

Is this via a secure https connection?

If content is missing or otherwise not working when a secure https connection is used then check if there is a shield icon to the left of the "Site Identity Button" (globe/padlock) on the location bar indicating that content is blocked.

• https://support.mozilla.org/kb/how-does-content-isnt-secure-affect-my-safety
• https://developer.mozilla.org/en/Security/MixedContent

These prefs are used to control this behavior:

• security.mixed_content.block_active_content
• security.mixed_content.block_display_content

• http://kb.mozillazine.org/about:config

Firefox 26 OS X10.9.1

After browsing a few minutes, FF seems to forget to load CSS from several pages. This keeps happening. I delete the cache, page is back to normal, wait 2 min, start from top. Am I the only one or is this known? http://cl.ly/image/1G1V2G2w1x03

This is not on https as well as http.

Should I be posting this in a new thread? This looks like a serious issue since 33 other people claim to have the exact same problem.

Here's an UNCONFIRMED ticket from 2010describing the same behavior on Windows7 so issue seems to be cross-platform: https://bugzilla.mozilla.org/show_bug.cgi?id=585489

You can try these steps in case of issues with web pages:

Reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• Hold down the Shift key and left-click the Reload button
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (Mac)

Clear the cache and cookies only from websites that cause problems.

"Clear the Cache":

• Firefox > Preferences > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox > Preferences > Privacy > Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe Mode start window.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Hi cor-el,

reload does not solve the CSS issue.

Clearing cookies does not resolve the CSS issue.

Clearing the cache does resolve the CSS issue: BUT, after 3mins the issue returns. This is not limited to a single site but happens to all site all over the web and keeps returning after working for a few minutes after resetting the cache.

This should really be addressed since it has happened for a very long time with several FF versions on OSX.

I tried FF27beta, same behavior. Guess I'll open a new ticket.

Did you try to reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files?

• Hold down the Shift key and left-click the Reload button
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (Mac)

That is usually sufficient in case of such issues.

True indeed. I experimented and on OS X Shift + CMD + R to reload the page fixes those RSS glitches. What I wonder is, why Safari and Chrome do not at all have any CSS issues that are similar.

So cor-el should I file a bug (it's still buggy behavior) or just move to another bug? Would be great to really address this problem.

Files should get corrupted or missing to make it necessary to refresh pages frequently.
It can happen occasionally in case something went wrong, either on the server or on its way to Firefox.
If it happens often then there is usually some security software involved or possible malware.

Well since that issue is not happening with webkit not chromium I assume it's due to Firefox.

But good news is: 28.0a2 (2013-12-28) works fine without having this CSS issue.

So I assume let's wait for FF28 to become a stable release and than switch back to that channel.

So funny: I experienced this with several software projects: the so-called unstable nightly aka developer-build works much better than the "stable" release.

For me, just add a line in your apache configuration file AddType text/css .css at file /etc/httpd/conf/httpd.conf

after that restart apache

service httpd restart

Thats work for me