react-bootstrap-table: Wrong header items width

The table header’s width is not calculated the same way as the table’s body, ending up in situations like this (note the header overflowing on the right):

[Edit: actually it happens even without this, see below] It happened because the bar on the left appears after a transition, and the whole layout re-rendered accordingly but the header did not.

[Edit: just missing CSS files] Also probably related: the width of a menu item is calculated before the sorting arrows are placed, which can produce this:

I could solve this by setting the width property, but I don’t want fixed with, and no minWidth prop is available.