Extra css for treestyle tabs

treestyletabs-extra-style-rules.css

/* This goes with mixed theme*/
.tab {
    background-color: #e2e2e2;
    background-image: url("https://i.imgur.com/l7XdlAC.png"); /*can't figure out how to use a local image here */
}
  
.tab .label {
  font-size: 10px;
  font-family: "Segoe UI";
  font-stretch: condensed;
  margin-left: 1px;
  color: hsla(0, 0%, 11%, 0.76);
}

.tab .favicon {
  margin-left: -7px;
  transform: scale(0.85);
}

.tab .twisty {
  margin-left: -10px;
  visibility: hidden;
}

.tab.active {
    background-color:hsla(0, 0%, 90%, 0.9)
}
#background {
  background-color: #6a6a6a;
  background-image: url(https://i.imgur.com/h1J04NS.png); /*can't figure out how to use a local image here, would definitely prefer to but I can't figure out where treestyle tabs puts this css */
}

I believe the issue that you can't load a local image is due to the limitation Firefox put on all plugins. This implementation should prevent malicious plugins from stealing your local data.