LayoutTests/fast/css-grid-layout/containing-block-grids.html - WebKit - Git at Google

 <!DOCTYPE html>
 <html>
 <head>
     <script>
         if (window.testRunner)
             testRunner.overridePreference("WebKitCSSGridLayoutEnabled", 1);
     </script>
     <link href="resources/grid.css" rel="stylesheet">
     <style>
         div { width: 100px; height: 100px; }
         .relative-positioned-grid { background-color: red; position:relative; }
         .relative-positioned-inline-grid { background-color: red; position: relative; }
     </style>
 </head>
 <body>
 <p>Grids can act as containing blocks for positioned content.</p>
 <div class="relative-positioned-grid grid"><div style="background-color: green; left: 0; top: 0"></div></div>
 <div class="relative-positioned-inline-grid inline-grid"><div style="background-color:green; left: 0; top: 0"></div></div>
 </body>
 </html>
	<!DOCTYPE html>
	<html>
	<head>
	<script>
	if (window.testRunner)
	testRunner.overridePreference("WebKitCSSGridLayoutEnabled", 1);
	</script>
	<link href="resources/grid.css" rel="stylesheet">
	<style>
	div { width: 100px; height: 100px; }
	.relative-positioned-grid { background-color: red; position:relative; }
	.relative-positioned-inline-grid { background-color: red; position: relative; }
	</style>
	</head>
	<body>
	<p>Grids can act as containing blocks for positioned content.</p>
	<div class="relative-positioned-grid grid"><div style="background-color: green; left: 0; top: 0"></div></div>
	<div class="relative-positioned-inline-grid inline-grid"><div style="background-color:green; left: 0; top: 0"></div></div>
	</body>
	</html>