Highlight tweets from a user you don't follow

highlight-forced-tweets.css

/* 
  Highlights in red, shrinks text, converts text to grey, and adds "NOT FOLLOWING" before username.
  The user ID used here is for @POTUS, which will one day become @POTUS45.
  Designed to help highlight tweets forced into your timeline by Twitter. Narrow execution.
*/

@-moz-document domain('twitter.com') {
  .tweet[data-user-id="822215679726100480"][data-you-follow=false] {
    background-color: #FDD;
    color: grey;
  }
  
  .tweet[data-user-id="822215679726100480"][data-you-follow=false] .stream-item-header:before {
    content: "NOT FOLLOWING ";
    color: black;
    text-decoration: underline;
  }

  .tweet[data-user-id="822215679726100480"][data-you-follow=false] * {
    font-size: 8pt;
    color: grey;
  }
}