Image blurry when box-sizing: border-box applied

[Crirlnemowero]

Can anyone tell me why the top image is blurry? http://blog.distance.mun.ca/technologyresources/why-blurry/The first has width and height set, and the second one has that removed. That's the only difference. I suspect the box-sizing property is throwing it off somehow. But I can't figure out why!Advice welcome!Thanksps: A good run-down on border-box: http://paulirish.com/2012/box-sizing-border-box-ftw/