All your external CSS files are empty. You need to open them in DW and add some device specific styles to each one.
phone.css
body {font-size: 10px; color: black; width: 320px}
tablet.css
body {font-size: 14px; color: red; width: 750px}
desktop.css
body {font-size: 18px; color: navy; width: 1000px}
Then add some Lorem ipsum or dummy text to your HTML document. Save everything and upload to your server.
If you resize your browser viewport, you should see different styles for each device. HINT: don't use IE to preview. Use a good browser like Firefox, Chrome or Safari.
Nancy O.
Alt-Web Design & Publishing
Web | Graphics | Print | Media Specialists
http://alt-web.com/
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