Improve popover's arrow appearance

[MewenLeHo]

Prerequisites

• I have searched for duplicate or closed issues
• I have validated any HTML to avoid common problems
• I have read the contributing guidelines

Describe the issue

Coming from #1803

The width of the border's arrow seems thiner and is missing 1 (or 2?) px.

It seems not related to the way CSS handle diagonal lines.

Reduced test cases

A solution can be to play with ::before (probably not the left/right values), and the border widths because the "white area" is too large and hides 1px from the 2px border of the arrow.

What operating system(s) are you seeing the problem on?

Windows, macOS

What browser(s) are you seeing the problem on?

Chrome, Firefox

What version of Boosted are you using?

v5.3.0

[louismaximepiton]

Already talked about this here,

Maybe a good solution would be bottom: round(calc(var(--bs-popover/tooltip-border-width) * sqrt(2))); ?