makes it easy to test your responsive design on a variety of devices.
Just enter a URL and then you can select a device from the drop down
menus, or you can simply drag the edges of the viewport to change to a
custom size. Click the rotate button to see the design as it would be
viewed in landscape or portrait modes. "
"Screenqueri.es is a Pixel Perfect Tool to test your Responsive Design / Media Queries. Select from Pre-defined Screen Resolutions OR Drag Screen Handles To Go With Your Custom Screen Resolutions."