Created by: MartijnCuppens
It turns out the height of date inputs (https://github.com/twbs/bootstrap/issues/18842) are increased by the padding on the pseudo elements and the fixed height of 1.5rem of the ::-webkit-inner-spin-button.
I've now reset these paddings and height instead of hacking with the line-height.
Codepen to play with: https://codepen.io/MartijnCuppens/pen/wvBLzvb?editors=1100