Have you installed any new add-ons?

if so try restart in safe mode and see if the problem still persist.

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode#w_how-to-start-firefox-in-safe-mode

Firefox 42+ has a new Tracking Protection feature that is enabled by default in Private Browsing mode. You can see a shield icon at the left end of the location/address bar when you are in private browsing mode that some content is blocked. You can disable this feature in "Options/Preferences > Privacy".

• Options/Preferences > Privacy: "Use Tracking Protection in Private Windows"

• https://support.mozilla.org/kb/tracking-protection-firefox
• https://support.mozilla.org/kb/control-center-site-privacy-and-security-firefox

Thank you. I've tried both suggestions, but it doesn't help. It has happened before (even though I had a different theme back then, but it wasn't the problem), and it the problem went away on it's own, but I still didn't know how to fix it.

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.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 remove cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

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

• Switch to the DEFAULT theme: Firefox menu button/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

Tried all and I also asked a friend to check my blog from their computer and he also doesn't see any options on my blog, it's not just me or the browser. So, I e-mailed tumblr support and I am waiting for their response or for them to fix it.

You can check the log in the Web Console for error messages and the Network Monitor (Firefox/Tools > Web Developer) to see if content fails to load or is possibly blocked.

• https://developer.mozilla.org/Tools/Web_Console
• https://developer.mozilla.org/Tools/Network_Monitor

Use Ctrl+F5 or Ctrl+Shift+R to reload the page and bypass the cache to generate a fresh log.

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

Make sure that you allow pages to choose their own colors.

• Tools > Options > Content : Fonts & Colors > Colors : "Override the colors specified by the page with my selections above"

Try "Never" if the default "Only with High Contrast themes" isn't working.

This setting affects background images.

See also:

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

I will show you a screenshot of what I got from the developer, truth is i don't understand much. And still nobody from tumblr support has answered me yet. I asked the theme maker, too (still waiting), but it appears to be my blog in particular and just since, may 2-3 days...