0. Get Chrome if you don't already have it
2. Goto Tools -> Developer Tools
3. Click the gear icon on the bottom right
4. Find the setting "Override User Agent", check it, and select the browser/device you want to emulate
5. Refresh your page and inspect it. This is how it will look on the device you chose. (You'll have to re-size the browser to a phone-ish size if you've selected a mobile phone device)
Don't see the user agent string you're looking for in the list? Look here (http://www.useragentstring.com/pages/useragentstring.php) for an extensive list of user agent strings you can copy and paste into the free-form textbox.