I'm getting a strange red background when I visit some pages using Safari. on Chrome the page is rendered in white normally.

I am not using any extensions and plugins.

How do I fix this bug?

Safari: Version 10.1.1 (12603.2.4) macOS: Sierra Version 10.12.5

enter image description here

Edit: I do not have the paint flashing feature turned on, I also noticed that this bug occurs on local images with a transparent background without any stylesheets (see image below).

I tried opening a local file image, and it opens normally on Chrome and Preview. However on safari, the images has a red background.

enter image description here

  • 1
    Which macOS version and Safari version are you using?
    – user61744
    Commented May 30, 2017 at 8:55
  • @pjctech Safari: Version 10.1.1 (12603.2.4) macOS: Sierra Version 10.12.5 Commented May 30, 2017 at 11:33
  • Ad blocker plus and ghostery are shown in the screen shot. Can you confirm you get red content when you make a new user account in macOS and use straight safari?
    – bmike
    Commented May 30, 2017 at 11:52
  • @bmike yes, I turned off AdBlocker and ghostly (and all the other extensions). same issue. I have updated the screenshot with the extensions removed. Commented May 30, 2017 at 12:42
  • 1
    Although you've turned off all extensions it'd still be good to test if you get this problem in a fresh user account (as suggested by @bmike ). To do this, go to System Preferences > Users & Groups and add another user. Then log into their account and test Safari.
    – Monomeeth
    Commented May 30, 2017 at 13:39

2 Answers 2


I think this is a feature for web developers called "paint flashing".

Right-click on a blank bit of a page and select "Inspect Element", this will open the Web Inspector in Safari.

In the top-right corner of the Web Inspector there are a few icons. One looks like a paint brush. On your machine I bet it is selected.

Click it to turn it off.

Screenshot of Safari Web Inspector showing Paint Flashing button


I'm encountering this bug in Catalina (10.15.2) in Safari (13.0.4) and Mail on my Macbook Pro (15" 2017). I've posted screenshots here: https://discussions.apple.com/thread/250979814?page=1

It definitely seems related to rendering, and can be partly improved by selecting things on the page/ in the email, but will often only be removed where the selection is present. I also see this red fill prior to the contents of a page rendering in a Safari window. I also see it in open email windows that were fine previously, but have to be re-rendered at some point.

I'm hesitant to reset Safari since that seems to not fix the issue. This problem seems relatively rare online, and I don't have paint flashing activated. Any other tips or ideas are welcome!

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