bug(timepicker) chevron icon doesn't look right with font-size 14px on html

[ghost]

Bug description:

When I set font-size: 14px on html and size of timepicker is small, chevron icon doesn't look right:

Is there any particular reason why width and height of the chevron don't match?

When I set the same size for both width and height, the icon looks fine with any root font-size

Link to minimally-working plunker that reproduces the issue:

https://stackblitz.com/edit/angular-xspxt3?file=app/timepicker-basic.html

Version of Angular, ng-bootstrap, and Bootstrap:

ng-bootstrap: 3.1.0

[pkozlowski-opensource]

Is there any particular reason why width and height of the chevron don't match?

Not that I recall... Would you mind sending a PR that brings those to the same values so we can see how it looks?