Image is not shown in full size even though the window would be large enough

[JanSellner]

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I noticed that images are not shown in full size when the lightbox is open even though the window would be large enough. This is especially visible for images showing text. Here is a fiddle showing the problem: http://jsfiddle.net/rwwtv2az/2/ (you have to remove the javascript part to see the problem).

The problem is caused by the -1 in the ratio calculation of the resize function

/* Note: -1 to avoid rounding errors */
var ratio = Math.max(
    w  / (this.$content.parent().width()-1),
    h / (this.$content.parent().height()-1));

It states that this is due to rounding errors but it causes the ratio to be slightly above 1 and hence makes the image slightly smaller.

In the fiddle I fixed this issue by applying the procedure only if the image is smaller than the parent. If you think this is a proper way of fixing the problem, I could make a PR.