画面を回転しても、viewportを320pxで固定したいとき ref: http://qiita.com/ituki_b/items/81af23d349ee139d72d3

file0.html

<meta name="viewport" content="width=320">

file1.html

<meta name="viewport" content="width=320">

file2.js

var agent = navigator.userAgent;
if (agent.search(/Android/) !== -1) {
    $('meta[name=viewport]').attr({'content': 'width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no'});
    $(window).bind('resize load', function(){
        $("html").css("zoom" , $(window).width()/320);
    });
}