There's a script that can switch it automatically, but if you could add a custom script you'd better just center the tabber with CSS.

What you did isn't even centering it for any screen not the exact same width as yours.

Also, why are you even use a tabber if you only have a single tab?

This tabber is actually a sub-tabber system. Below the Supereminent Condition, there's physical capabilities described section by section, and the third sub-tabbers row is application of these.

Here's the screenshot example of each tabber having so much information they aren't seen close to each other.

And yes, you're right, with zooming out the page the tabber stays not certainly in the center. So how can I center it?

If you're an admin on the wiki and can edit the wiki's CSS, you can use that.

You can use the code here to make all tabbers in the wiki centered.

If you don't want all tabbers centered, you'd better have a clear criteria of which tabbers should be centered because applying it on a one-by-one basis is problematic.

So your criteria is that every tabber with only one tab would be centered?

Pretty much like it.

Use this:

.mw-parser-output .wds-tabs__tab:only-child {
    margin-left: auto;
    margin-right: auto;
}

It would affect all single-tab tabbers in the wiki. If you need it to affect only specific pages - that would require an additional condition. But I guess tabbers with just one tab aren't very common.

Alright, but to be certain and have no mistakes at it, where to insert it? CSS?

Yes