ios7 css 适配

<script>
if(/android/i.test(navigator.userAgent)) {
document.write('<meta name="viewport" content="width=device-width,minimum-scale=0.5,maximum-scale=3.0,user-scalable=yes" />');
} else {
document.write('<meta name="viewport" content="minimum-scale=1.0,maximum-scale=1.0,user-scalable=no" />');
}