Created by: NielsHolt
Hi
This PR will change the dimensions of popover and tooltip from px to rem AND fix a bug in the way the arrow of popover and tooltips are placed. The current placement of the arrow is only centered on the element when border-width and arrow-width are default values. This PR will allow both border-width and arrow-width to be changed
It need to be merged/integrated with #23763 (closed)
Could solve #23793 (closed) and issues in #23468
Setting $border-width: 20px; $popover-border-width:10px; in Bootstrap 4-beta would give
In this PR (with $popover-arrow-width: 1rem;) it would be
