Selkirk Lighthouse in Pulaski, New York. Built in 1838, the Selkirk Lighthouse is one of the few lighthouses left with the unique birdcage-style lantern. It sits near Lake Ontario on the Salmon. Lighthouse is an open-source tool for testing the performance of web pages through Google's PageSpeed Insights API and was released as an extension for Google Chrome in 2016. Now that the Mozilla.

This article deals with websites not appearing correctly in Firefox.

• If you receive error messages when trying to load websites, see the Websites don't load - troubleshoot and fix error messages article instead.
• If any of the more specific articles below apply to you, see those articles first:

Table of Contents

Firefox caches websites, which means it saves some files on your machine so that it doesn't have to re-download everything when you visit sites. If a website has updated their code, Firefox may still be using some of the old code along with some of the new, which can make a web page display incorrectly. To fix this, you need to clear the cookies and cache:

1. Click on the menu button to open the menu panel.Click the Library button on your toolbar. (If you don't see it there, click the menu button then click Library.)
2. Click History and select Clear Recent History….
3. In the Time Range to clear: drop-down, select Everything.
4. Below the drop-down menu, select both Cookies and Cache. Make sure other items you want to keep are not selected.
5. Click .

Some websites may not look right at different zoom levels. To reset Zoom setting, for the site, press Ctrl + 0command + 0 and for all sites, see the documentation about the Zoom add-on you use.

Some sites do not display properly with a minimum font size. To reset the minimum font size:

1. In the Menu bar at the top of the screen, click Firefox and select Preferences.Click the menu button and select ...
2. Select the Content panelGeneral panel and navigate to Language and Appearance.
3. In the Fonts & Colors section, click .
4. Change the Minimum font size to None.

You may have inadvertently set the page style to No Style. To ensure Firefox is set to use the page's default style:

• Press the Alt key to temporarily bring up the traditional Firefox menusOn the menu barAt the top of the Firefox window, click on the View menu, then select Page Style, then click Basic Page Style.

Now that the page is using its default style, it may be displayed correctly.

You should check whether you have an extension (such as NoScript) or Internet security program (such as a firewall, antivirus, or anti-spyware program) that can block JavaScript.

Firefox Lighthouse Group

In some instances the loading and verification of secure web content will be time-dependent, so you should check that date, time and timezone are set correctly on your system.

Some extensions may interfere with the way websites are displayed or your graphics card and drivers don't display some web content correctly when hardware acceleration is turned on. Follow the instructions in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to see if one of these is causing the problem.

Occasionally you may come across a page that simply doesn't work in Firefox. If that happens, please report the problem by visiting Webcompat.com.

If you are using Firefox Beta, Developer Edition or Nightly, click on the page actions menu (three dots in the address bar) and select Report Site IssueYou can also go to the Firefox menu and click Help, then select Report Site Issue.

Firefox Lighthouse Windows

Based on information from Websites look wrong (mozillaZine KB)