My css tweaks for Twitter - install using e.g. Stylish addon for Firefox (https://addons.mozilla.org/en-US/firefox/addon/stylish/)

twitter.css

@namespace url(http://www.w3.org/1999/xhtml);

@-moz-document domain("twitter.com") {
  .stream-item .promoted-tweet {
    background: #ff9080;
  }

  /* you might like / in case you missed */
  .stream-item.has-recap, .stream-item.has-recap .stream-item {
    background: #ccffdd;
  }

  /* expanded tweet */
  .stream-item.open {
    background: rgba(238,255,204,0.5);
  }
  
  /* override for other tweets in expanded conversation */
  .content-main .expansion-container .tweet.ancestor, .content-main .expansion-container .tweet.descendant, .content-main .expansion-container .view-more-container, .content-main .expansion-container .inline-reply-tweetbox {
    background: rgba(208,255,150,0.5);
  }
}

Not using them anymore, using tweetdeck instead..