Example Problem: layout.css.devPixelsPerPx I somehow had the idea that things in about:config were also configurable via the userChrome.css. Is this true? Is it true, for example, with layout.css.devPixelsPerPx? If so, what is the equivalent CSS selector? Also, will changes to the css file over-rule changes in about:config, or vice versa? Answer: not much overlap From It_Was_The_Other_Guy1, it appears that there is rare overlay between the userChrome.css and the settings in about:config.

Intro I use several three-monitor setups and one of the setups has a large TV-size screen as the monitor. I typically put my browser instances over there and need to shrink them to a more zoomed-out level to make websites usable at that size. The answer was to change the layout.css.devPixelsPerPx in the about:config1. I changed mine to 0.8, which was equal to about the 80% zoom level which works for me.

Intro I use Firefox Mobile, which tries to install the PWA (Progressive Web App) of sites whenever it finds a manifest file; otherwise it allows installation to just add a Firefox link to the site instead, which is what I want. This can be done with the Ublock plugin1. I’m struggling to find the right syntax for this; I believe I want a static filter that applies to any site. An example of the line that brings the manifest from Google Photos is this:

Don’t do webdev work in your personal browser account Opening dev sites in your primary browser/account is problematic. Opening in Private (FireFox) or Incognito (Chrome) is a must, since it usually turns off caching and removes you from any left-over accounts that might be interfering with your validation. I’ve always done dev sites in my dev browser, so good to hear a group that recognized (sort of) this: https://polypane.app/blog/always-open-localhost-in-your-development-browser/ And disclaimer: Polypane who wrote the article is a paid browser (after 2 weeks).

My userChrome.css doesn’t seem to be doing what it did previously, and the text in my URL-bar is far too small. Here’s what fixed it in my userChrome.css previously: #urlbar {-moz-appearance: none !important; font-family: Tahoma Bold !important; color: Black !important; font-size: 16pt !important; } but it doesn’t seem to be doing anything now; change the font-size and restarting Firefox doesn’t seem to make any difference. Why is it behaving differently now?

Using bufler1 and selectrum2 to navigate browser buffers concisely. Firefox plugin Because one of exwm greatest benefits is using emacs’ in-built buffer methods for navigation, it is handy to include the address of any website in its title so the buffer can be found by just searching, e.g., “slack”. For this reason the misleadingly named “KeePass Helper"3 is tremendously useful. Now I can easily select my buffers with a random-access method off a portion of the URL.

C-w is already a highly used shortcut system-wide on my machine, so I’d like to make a different shortcut for close-tab – say, F4. How can I make this change in Firefox? I felt the frustration of several Firefox questioners who asked the same thing and were answered as if they just didn’t know the shortcut, missing the point entirely. On Reddit, though, I receive two excellent answers. One is the easy solution, with a handy plugin that takes care of it.

Version at time of writing: Firefox 79.0 First, locate your profile by going to the firefox menu bar: Help -> “Troubleshooting Information” and find on the page “Profile Directory”. Navigate there, where you’ll be making/adding two files that allow you to customize behavior and appearance of Firefox. For reference, mine was here: ~/.mozilla/firefox/aabkj82t.default/ . Yours will have some other blob of random characters before “.default”. userChrome.css This file should definitely exist already.

For years I’ve had shortcuts in Firefox. In this example, I’ve long been able to type i thing in my URL-bar and it would immediately take me to a google image search for “thing”. In the past this was added by right-clicking “search” on some page and selecting “add a shortcut for this search”. At some point, though, that went away. The functionality is now hidden a little, and you solve it with bookmarks (which I also haven’t used in any form for years).

Things were going great on my Fedora 20 system. My system downloaded a new Shockwave Flash version, which is always good knowing their terrible security problems. But next thing I know my firefox is yelling at me on almost every web page, refusing to start Flash because it’s an old, insecure version. I check my versions and Firefox tells me flash is 11.2.202.438 (sheesh! Adobe is serious about version numbers) when those last digits are supposed to be .