Thanks for getting back to me!
Just in case my explanation wasn’t clear, I made a quick GIF to show what I mean.
As you can see in the GIF, after I drag the bases-table-header-resizer, the total width of the table header no longer spans the entire width of the table.
So, I just want to double-check, is this layout behavior by design/intentional?

The CSS code used in the GIF is below:
.bases-thead {
height: 100px;
}
.bases-tbody {
background-color: red;
}