How did git dots are displayed over the website

Navigating to website https://github.blog/2020-12-15-token-authentication-requirements-for-git-operations/

Pasting the screenshot , its a public domain website so I dont think there would be content copyright issues

I like the dotted pattern on the webpage . I first thought its an image but when I did Inspect element nowhere I was able to see the image or any css style that was applied to display those dots. How that dotted pattern is acheived ?