Decimal Size?

I'm using a Bootstrap template that I bought and it has some decimal size for regular feather icons. The way they did it was to set the width and the height of the feather icon on the element itself, for example:
<span data-feather="x" style="width: 12.8px; height: 12.8px;"></span>

This will make the feather icons width and height becomes 12.8 (checked using inspect element).

But in Svelte Feather Icons, I can just do:
<XIcon size="12.8" />

Well except that I think Svelte Feather Icons don't accept decimal value. I guess it got rounded down to the nearest integer because when I check it with inspect element, it becomes 12.