css-validator-bug / font-weight ???

hi,

it seems, that the validator shows the following bug:
http://jigsaw.w3.org/css-validator/validator?uri=http://www.ub.uni-rostock.de/ub/index_xde.shtml&warning=no&profile=css2

"Ungültige Nummer : font-weight 300 ist kein font-weight-Wert : 300"

but i think 300 is a valid value in the css-definition:
http://www.w3.org/TR/REC-CSS2/fonts.html#propdef-font-weight

best regards,
joerg.