@import ("at-import") With Negated Media Type in Lower Case CSS Filter

If the background color of this paragraph is green (a darker green than this page's background) then the hack was applied.

Example Code

Two style elements are used here because of the cascading order and because @import rules must come before all other rules in a stylesheet.

<style type="text/css">
p.test {
  background-color: #f66;
<style type="text/css">
@import url(filters_test.css) not all;

List of browsers that apply this

List of browsers that do not apply this