To display the content correctly on mobile platforms as well, include this in your HTML :
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
There's many problems with your HTML. All your content is outside of your body. Your CSS syntax is invalid. You can't just add curly braces and put CSS inside your HTML tags. You either have to use the style property, or a style tag. Alternatively, use an external CSS file, this is generally the best practice.
Pieter