Hi Tim, centering things vertically has historically tended to be a tricky area of HTML. There is a mechanism in recent years called flexbox which tends to be the easiest way. If you look at the stock CommandBar.htm you'll see a few things that are centered are using a <vcenter></vcenter> tag around them which will use a flexbox to do it. That's the easiest.

But needing to center those buttons is an indication that other some of your other UI is too tall. The stock command bar is carefully designed so that those buttons are the tallest things so they take up the entire height and thus don't need centering and can also benefit from Fitt's law for targeting them.

- Michael