Add close tab animation so that other tabs animate smoothly into their new position

[kenneth-ge]

Currently, opening a new tab causes the other tabs to slide down into their new position. However, when a tab is closed, the new tabs teleport instead. This animation inconsistency is jarring and fixing this could add some awesome polish!

If this is a CSS/HTML animation situation, I'd be more than happy to take a look and implement this myself if someone can point me in the right direction