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How to show browser widths in Firefox- is there an add-on / command to show browser widths when moving right side of screen

  • 4 replies
  • 1 has this problem
  • Last reply by cor-el

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Does Firefox have the ability to show browser widths (px) when I am checking various browser width results in website design? Chrome has this in Developer tools - it displays as a little indicator at the top of the screen - but I don't want to resort to Google! I am aware of the developer tool in Firefox to set browser viewport size but this doesn't solve my problem. In responsive web design It is useful to move the right side of the browser in and out to check web design results dynamically (at different widths). Sorry if this has been answered elsewhere.

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Firefox has a Rulers feature that I think will do what you want. The button is not on the DevTools bar by default, you have to add it. For more info, see:

Does that work for you?

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Thanks jscher2000! yes that’s what I needed. I had read about the rulers but was having trouble finding it. The only downsides of Firefox rulers tool seems to be that the rulers appear not to be persistent and always need the web console open. Am I right here? It seems that whenever Firefox is restarted the web console needs to be opened again and the rulers need to be “clicked” again. Is there a way to automatically keep the “rulers” active when Firefox starts? Your response somehow also led me on to an add-on, “Viewport” (extension) which is persistent and seems to solve my problem. Now there is an issue that “Viewport” and the Firefox “rulers” show slightly different pixel widths … I would prefer it if the Firefox Rulers was persistent. Anyway, thanks heaps for your help.

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Hi rayway, all I know is what I saw on MDN. I don't actually use it myself.

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There seem to be problems with the width of the scroll bar according to some comments: