The [semi-?] official CSS validator complains about some MS CSS

Question

I ran Site.css (mostly Microsoft-supplied CSS, with maybe 5% added by me) against http://jigsaw.w3.org/css-validator/validator, and it told me I had two errors:

.featured .content-wrapper   Value Error : background-image left is not a color value )
.boldHeader  Value Error : font-style bold is not a font-style value : bold

I removed the second one (which was my error), but the first one was this MS CSS:

background-image: linear-gradient(left, #7ac0da 0%, #a4d4e6 100%);

What is wrong with it?

BTW, it also gives me these warnings:

Property -webkit-box-sizing is an unknown vendor extension
Property -moz-box-sizing is an unknown vendor extension

Answer 1

according to the spec, you need to specify an angle or a direction as the first parameter to gradient():

Formal grammar: linear-gradient(  [ <angle> | to <side-or-corner> ,]? <color-stop> [, <color-stop>]+ )

You're missing the to in front of left.