Use "parseFloat" instead of "parseInt" for when sub-pixel css values are used

I was experiencing `original` never being `height` in `adjust()` because one had sub-pixel accuracy and the other didn't.
The underlaying reason was a padding of 10.25px.
I think CSS values can contain fractions of pixels and should be parsed as such.

@jackmoore wdyt?
@vogdb @tomaszdurkafyi