Hide blue glow on Firefox pinned tabs

If you're like me, you get easily distracted by shiny things, e.g.

Any time Firefox notices the page changing the document.title, it sets the titlechanged property on the tab CSS. Turns out this is easy to see with the DOM Inspector:

Given this information, now I can craft a userChrome.css file to nuke that CSS rule:

.tabbrowser-tab > .tab-stack > .tab-content[pinned][titlechanged]:not([visuallyselected="true"]) {
  background-image: none !important;
}

And the blue glow is gone!