Fix: third card item's right border not showing

[juliejgiles]

Issue:

Outer right carousel item has its border hidden at certain screen widths:

Cause
When an odd number of cards are used in the carousel, the sum of all card widths and spacing exceeds the container so the outer right border of the last item is hidden due to the container's overflow:hidden css property (https://github.com/rcbyr/keen-slider/blob/master/src/keen-slider.scss)

For example, by overriding keen-slider 's css to overflow: visible, the border will show up again.

Fix
Round down the card size where it is not a whole number.