How to set condition for all posts with one label

My blog is total 10 post's, 5 post's with 'job' label and 5 "admit card" label I set condition for 'job' label

b:if cond='data:blog.post.label == "job"'!-- for label 'job' --style.body {width:1200px;}/style/b:if

That is, whenever there is a post index of the job label, then the style (body width) the change