test/e2e/resources/elements/css-supports.html - devtools/devtools-frontend - Git at Google

 <!DOCTYPE html>
 <style>
   div {
     width: 0px;
     height: 0px;
   }

   @supports (width: 10px) {
     .rule1 {
       width: 10px;
     }
   }
 </style>
 <div class="rule1"></div>
	<!DOCTYPE html>
	<style>
	div {
	width: 0px;
	height: 0px;
	}

	@supports (width: 10px) {
	.rule1 {
	width: 10px;
	}
	}
	</style>
	<div class="rule1"></div>