adding the following css in the userContent.css file

```css

#TabsToolbar .tabbrowser-tab .tab-content {
   font-weight: 800 !important;

} ```

if you want to customize firefox, there is a repo you may be interested in

https://github.com/Aris-t2/CustomCSSforFx

Thanks very much for this. I already have a css file - the purpose is to put tabs on bottom. I definitely did not write it - just copied it from the web.

Do I take the code you have above and tack it onto the end of the one I already have? Or do I create a different css file for this?

Thank you so very much!

PS - I looked at the link you included, the "repo" and it was like Greek to me. No clue what it's even trying to teach me. You youngsters are so lucky that this is what you are all growing up with, and that it seems self-evident. :)

Yes, you are correct throw in

#TabsToolbar .tabbrowser-tab .tab-content {
  font-weight: 800 !important; }

the css file you already made for tabs on the bottom and save it, and exit and restart firefox and it should have made the tab font bolder.

Oh, sorry. I thought you're a developer.

if you're using Mac

Steps:

1. locate the firefox user profile folder

in `Finder`: `Command+shift+G` input `/Users/lirui/Library/Application Support/Firefox/Profiles` if u are using `Firefox`(this is the folder firefox save all the user-related settings, bookmarks, extension, ...etc)

2. go into the folder looking like`******.default`,

3. create a file named `userChrome.css` (if not existed in the folder)

4. open the file and add the following code(from "#" to "}")

\#TabsToolbar .tabbrowser-tab .tab-content {

  font-weight: 800 !important;

}

5. restart firefox

If you're using Windows

1. the first step is different from mac, ref. to https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data to locate the user profile folder.

2. follow step 2-5

THANKS YOU GUYS!!! IT WORKED!!!~