Default style has changed in v9

[stropitek]

It seems like this commit changed the default appearance of the react-datepicker component.

The unit changed from rem to em, which means everything was multiplied by 0.8 compared to before, which does not seem intentional reading the commit message:

The default appearance remains unchanged since the root element still
uses font-size: 0.8rem.

v8: units in rem, so relative to the document's root element.
v9: units in em, so relative to the parent, which is set to 0.8rem, which effectively reduces those sizes.

Appearance in v8:

Appearance in v9:

[martijnrusschen]

Apologies, missed that one. We can move that to 1rem to be consistent with the < v9 versions while still allowing relative font sizes.

[stropitek]

If we change the base size on the .react-datepicker element, it will restore certain properties but change the font size:

For a non-breaking change using em, I think we need to go through all the values which were changed from rem to em and divide them by 0.8

I can do a PR if you want.

[martijnrusschen]

If you're able to help, please submit a PR that would be great. Thanks!