Well, there is another situation which is the content between the brackets in css url is not always have quotes, like background: url(/img/static.jpg), and this is legal, but when this situation, the replace part when you are using the manifest, it won't work.
Well, there is another situation which is the content between the brackets in css url is not always have quotes, like
background: url(/img/static.jpg)
, and this is legal, but when this situation, the replace part when you are using the manifest, it won't work.