Hi, there is no design changes. You are having issues with the program itself <blockquote> It happens on EVERY WIndows7-based PC with EVERY Firefox installation in default configuration (no tweaks, no themes). </blockquote> Fortunately the above is untrue as to all Firefox Installs everywhere. Separate Security Issue, please update your : Flash 22.0 r0 By using this https://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html As the above is so old. Flash Player Version: 29.0.0.171 Current Version https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, . . . .) Note: Other software is offered in the download. <Windows Only> Please do this : In your Windows Search Bar in the Start type CMD.exe and Right Click it to Run as Administrator From the Command Prompt type or Copy/Paste Sfc /scannow ( Sfc<space>/scannow ) then Enter. When it is finished please reboot. Then please do this : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : *https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles *https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer Reinstall with Current Release Firefox 60.0.1 with a Full Version Installer *https://www.mozilla.org/firefox/all/ Please let us know if this solved your issue or if need further assistance.

Also please : https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration