Fix sizing inconsistencies in native vs non-native Popover

[acelaya]

We have recently discovered that the Popover can get incorrectly sized in browsers which do not support the native Popover API (this can be mimicked by explicitly setting asNativePopover={false}). This is due to the fact that the popover is sized based on its most immediate relative container in that case.

It's worth mentioning that it's likely not possible to achieve full look-and-feel parity, but at least the sizing should be equivalent, or at least document this difference to take it into consideration.

[acelaya]

One way we worked around this recently was by setting tailwind's w-max, which sets width: max-content. This is the default behavior for native popovers.