>it also put that bar of color on either side of the tab name as shown in the first post of this thread.
The only time I've seen that happen is if you comment out starting from:
.australis .tabbrowser-tab .tab-background-middle,
Instead of from:
.australis .tabbrowser-tab .tab-background-start,
But for me, with 23.6 (from auto-update) and 23.8 (link on this site), all is well by default.