Can you post a link to a publicly accessible page (i.e. no authentication or signing on required)?

Can you attach a screenshot?

• https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem
• use a compressed image type like PNG or JPG to save the screenshot

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• hold down the Shift key and left-click the Reload button
• press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• press "Command + Shift + R" (Mac)

Clear the Cache and remove the Cookies from websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Remove the Cookies" from websites that cause problems:

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Manage Data

"Clear the Cache":

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Clear Data -> Cached Web Content: Clear

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History").

Using "Forget About This Site" will remove all data stored in Firefox from this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of involved files.

If you revisit a 'forgotten' website then data from that website will be saved once again.

• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

Thank you for your reply, I had tried most the things you suggested, except for the "forget page" from History

I am uploading a screenshot from one of the websites, https://sindri.is/

It contains a a normal version, working on another computer and then the one with the font problem, you should notice the difference

Can anybody help me, the latest 66.0.4 did not fix this, I have all latest drivers and BIOS and this is a horrible problem for me!

This is either a Firefox problem where a different font is used or special font settings applied or a Windows problem with ClearType or other font settings.

You can right-click and select "Inspect Element" to open the builtin Inspector with this element selected. You can check what font family and font settings are used for selected text in the Rules tab and what is actually used in the Font tab in the right pane of the Inspector.

• https://developer.mozilla.org/en-US/Tools/Page_Inspector
• https://developer.mozilla.org/en-US/Tools/Page_Inspector/How_to/View_fonts

Hi it´s always the same font: Lato

Sometimes the font renders fine, I can have some tabs open with the same exact open and the font is fine in some tabs but broken in another.

If the website opens with the font correctly rendered, I stays like that if I browse through that same tab, but if open any links in a new tab, the font on the new tab is distorted, I would provide a screenshot but at the moment I only have the broken font rendered

I have found the source of the problem, when I was trying to delete the Lato font from my system I noticed it kept being added on by Adobe Creative Cloud. After removing the font and Adobe Creative Cloud everything renders fine, now I just need to install the font again to my system and make it work with Adobe Creative Cloud.

This is a very weird bug, it only affected Firefox and only some of the pages with the Lato font.

Firefox would normally download the Lato font from the web page as instructed via an @font-face CSS rule. A locally installed Lato font that is a different version may cause issues.