I do a lot of work with Firefox, as its developer tools outshine all the other browsers, hands down. But recently I’ve been getting a lot of sites appearing without CSS. As it turns out, there’s actually “mixed content” on the page, and the default security setting is to block that content. Normally I agree with security settings in general, but I know what I’m doing, and this is just a massive annoyance. There are ways around this though.
1) You can add the toggle mixed content add-on from here https://addons.mozilla.org/en-us/firefox/addon/toggle-mixed-active-content/
2) However, my preferred method is to disable the feature in the browser by doing the following.
Enter about:config into the Firefox address bar (confirm the info message in case it shows up) & search for the preference named security.mixed_content.block_active_content. Double-click it and change its value to false.
After this, you’ll be browsing without that annoying security blockage, and everything will feel back to normal.