If you want to change the colorful webpage to gray for special reasons, you only need to <html>add the attribute filter: grayscale(1); to the label of the webpage
Initial web page:
Grayed webpage: Click F12, open "Developer Tools", click "Elements", add the attribute filter: grayscale(1); to the <html>label, and the page can be grayed out, as follows
Turn off the "Developer Tools", as shown in the figure:
