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How to change the font-size of Thunderbird thread list on a Mac?

I don't see any settings in the preferences.

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Set it up 11 intead and it will display better – user64878 Jan 26 '11 at 18:31

You need to edit your userChrome.css.

Go to ~/Library/Thunderbird/Profiles/[yourProfileName]/chrome/ (creating the chrome directory if it doesn't exist) and edit userChrome.css, again creating if it doesn't exist.

For example, to edit all text in Thunderbird (except message view), enter the following:

/* Global UI font */
* { font-size: 18pt !important;
  font-family: Verdana !important; 

The result looks something like this:

alt text

Unfortunately, I was unable to find the CSS class for the message list. Replace the * in the css with that css class and it should work as intended.

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Yes, this example is exaggerated, but how else can I prove it works? – Daniel Beck Jan 26 '11 at 18:30
This solution only helps a little bit, because you only increase the font - but you need to add space for that larger font as well. – user111964 May 31 '12 at 13:43

Daniel's answer is correct. You have to extend userChrome.css. Here is CSS code that will fix the spacing as well:

/* set default namespace to XUL */

/* Set Font Size In Folder Pane */
#folderTree >treechildren::-moz-tree-cell-text {
    font-size: 12pt !important; }

/* Set Font Size In Thread Pane */
#threadTree >treechildren::-moz-tree-cell-text {
    font-size: 12pt !important; }

/* Set Height For Cells In Folder Pane */
#folderTree >treechildren::-moz-tree-row {
   height: 25px !important; }

/* Set Height For Cells In Thread Pane */
#threadTree >treechildren::-moz-tree-row {
   height: 25px !important; }
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I use the "Theme Font & Size Changer" add-on:

This add-on gives you a little GUI, where you can easily change the font-size of the thread-list (and the tree), without fiddling around in the css file.

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Please read How do I recommend software for some tips as to how you should go about recommending software. At the very least you should provide more than just/at least a link, for example some additional information about the software itself, and how it can be used to solve the problem in the question. – DavidPostill Sep 4 '15 at 11:57

You have to make a folder named chrome in the profile folder. On a Mac it is located in /users/NAMEOFTHEUSER/Libraries/Thunderbird/Profiles/NAMEOFTHEPROFILE/ and there you need to make a new text file named userChrome.css, as discussed in the previous answers.

listitem, treechildren::-moz-tree-row {
    min-height: 2em !important;
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Can you expand your answer to explain where the user is meant to enter this code and what it will do? – Burgi Mar 17 at 15:03
You have to make a folder named "chrome" in the profile folder. On a Mac it is located in /users/NAMEOFTHEUSER/Libraries/Thunderbird/Profiles/NAMEOFTHEPROFILE/ and there You need to make a new text file named userChrome.css. Just like the previous answers told – Nikola Kołodziejczyk Mar 18 at 17:59
I suggest you have a read of How to write a good answer. It will explain how SuperUser works and hopefully in future prevent you from having answers deleted or from receiving downvotes. – Burgi Mar 18 at 21:27

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