http://stackoverflow.com/questions/11147741/google-maps-on-website-for-phone-browser-is-too-small

Basically the article explores the difference between physical pixels and CSS “pixels”. There is a scale factor between the two. Its default value on most mobile browsers seems to be the reason why you often see pages designed for desktops looking very “zoomed out” with tiny text on a phone. And it also seems to cause unreadable Google Maps!

My problems went away when I added this HTML snippet into my “head” section:

<meta name="viewport" content="width=device-width">

http://map.yueme.us