Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Window size won't go below 410px in v.26

  • 7 replies
  • 34 have this problem
  • Last reply by printphi

more options

My Firefox auto-updated to v.26 today. Since then, the smallest size I can shrink my browser to is 410px wide.

This is for all websites.

I am a web developer and frequently use Firefox to develop sites for mobile devices. So this is very annoying!

I've tried reseting FF to it's default settings but this did not fix the problem (it just uninstalled all my plugins!)

Am I missing some settings somewhere?

Chosen solution

The add-on did not work either. So far setting it to Responsive has worked the best for me.

Read this answer in context 👍 0

All Replies (7)

more options

That is caused by this CSS rule for the main window.

  • chrome://browser/content/browser.css
#main-window:not([chromehidden~="toolbar"]) {
  min-width: 390px;

You can use an overriding rule in the userChrome.css file with a lower min-width.

@namespace url(""); /* only needed once */

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

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.

Modified by cor-el

more options

Hi Cor-el,

Thanks for your reply. That didn't seem to work.

My profile didn't have the Chrome folder in there. I create one, and put the CSS file in there, reset FF... but nothing.

For the time being, I can use tools > web developer > responsive design view but it's not as intuitive as actually resizing the browser window using dev tools.

I notice that Chrome has the same bug / feature. Do FF26 and Chrome run off the same settings?

more options
more options

"My profile didn't have the Chrome folder in there."

The folder name chrome needs to have a lower-case c - Firefox won't recognize Chrome (with an upper-case C) as a valid folder.

more options

Also make sure that you didn't save the userChrome.css file as a text file because that will Windows make to add a hidden .txt file extension (userChrome.css.txt).

You can see the real file extension (type) if you open the Properties of the file via the right-click context menu.

more options

Chosen Solution

The add-on did not work either. So far setting it to Responsive has worked the best for me.

Modified by jeffhlsk

more options

toddy victor on December 20 said, "See if this addon works"

This Add-on says, in red: "Not available for Firefox 26.0."

I had three windows set up next to each other with no problems for about a year. They would retain their size and position with every restart, etc. With the 26.0 update, I can no longer use them together because they are now all too large. I hope that this is a bug and will be fixed without my having to jump through a lot of hoops to work around the problem, since I am NOT a techie!