With the introduction of the CSS3 @namespace rule most web developers get confused by the order in which the at-rules must appear. First of all, there are three types of at-rules that must be put at the very beginning of a style sheet: @charset, @import and @namespace. Before the adoption of the @namespace rule, the order was the following:
@charset@import
Now the order has been changed, because the @namespace rule is at the bottom of the list:
@charset@import@namespace
As you can see, the order reflects the new status of CSS at-rules.