Html5/CSS3 Media Query

I made a new html document with only a PDF-file in it. The code:

<embed src="impressum.pdf" width="1200" height="900" alt="pdf" pluginspage="http://www.adobe.com/products/acrobat/readstep2.html">

It workes perfectly but my problem is now, that I don´t know how to format it for the smartphone view. I started with the regular Media Query code in css and don´t know what I should put in there:

@media screen and (max-width: 800px) {  
}