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http://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F%2Fwww.whatwg.org%2Fstyle%2Fspecification&profile=css3&usermedium=all&warning=1&vextwarning=&lang=en 0 is not a box-shadow value : 0 0 25px #ffa http://www.w3.org/TR/css3-background/#ltshadowgt
works not for box-shadow (still some wrong errors in that page, like @page...)