how to diagnose horizontal scroll that will not go away on mobile site

body {
    overflow-x: hidden;
    width: 100%;
}

<meta name="viewport" content="user-scalable=no, width=device-width, initial-scale=1.0" />
<meta name="apple-mobile-web-app-capable" content="yes" />

<meta name="viewport" content="user-scalable=0;"/>