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Cannot resize Firefox window under 374 pixel

  • 4 replies
  • 38 have this problem
  • 6207 views
  • Last reply by jscher2000

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Using Firefox 26.0, completely fresh download and install.

For various purposes I would like to be able to re-size the entire Firefox window to a width below 374 pixel, however this is not working anymore. It simply stays wider or equal to 374 pixel. Before I did the update to 26.0 this worked just fine.

Of course I can do this with web developer but I prefer to have the entire Firefox window at 200 pixel or 300 pixel width for example.

Chosen solution

Note that with the bookmarklet you will probably run into security issues as Firefox doesn't allow some page to open such a pop-up.


You can hide all toolbars in a new window and use code in userChrome.css to set a smaller min-width.

Add code to the userChrome.css file below the default @namespace line.

The customization files userChrome.css (user interface) and userContent.css (websites) are located in the chrome folder in the Firefox profile folder.

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

#main-window:not([chromehidden~="toolbar"]) {min-width:200px!important;}

See line 8:

  • chrome://browser/content/browser.css
Read this answer in context 👍 7

All Replies (4)

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Yes, this is in preparation for the Australis UI refresh, because the location bar was getting cut off at smaller widths in the new design. The temporary workaround is to use window.open() to launch a window in the size you need. See: Resize Firefox 26 to a width of less than 400px.

Modified by jscher2000

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Chosen Solution

Note that with the bookmarklet you will probably run into security issues as Firefox doesn't allow some page to open such a pop-up.


You can hide all toolbars in a new window and use code in userChrome.css to set a smaller min-width.

Add code to the userChrome.css file below the default @namespace line.

The customization files userChrome.css (user interface) and userContent.css (websites) are located in the chrome folder in the Firefox profile folder.

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

#main-window:not([chromehidden~="toolbar"]) {min-width:200px!important;}

See line 8:

  • chrome://browser/content/browser.css

Modified by cor-el

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Since I prefer to make the customization in the "roo"t of the browser UI style I chose to edit the userChrome.css and now it works. Thank you cor-el!

jscher2000, I don't know what this Australis UI refresh is, but I highly doubt that people that resize the browser windows to under 200 px or under 300 px still need a location bar. I would more assume this is for development purposes rather than browsing, however I do respect Mozilla's decision to set a min-width.

Where can one read about these tiny little changes from version to upgraded version please? Would be great to not have to wonder next time (do I have a faulty install, virus, is it a bug, etc..) but see "ah this is going to be different and this is how I can change it to the way I like it".

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The release notes always link to hundreds of individual bug reports detailing changes. It's the tiny "complete list of changes" link: http://www.mozilla.org/en-US/firefox/26.0/releasenotes/

For some reason, the dynamically generated list doesn't include this particular change: 897160 – Set a minimum width for the Firefox window.

Note about the bug tracking system: it's generally not helpful to add comments to closed bugs. See: