此做法前提，需要 iframe 內容在相同網域下
<script>
$('iframe').load( function() {
$('iframe').contents().find("head")
.append($("<style type='text/css'> .my-class{display:none;} </style>"));
});
</script>https://stackoverflow.com/questions/6494721/override-body-style-for-content-in-an-iframe
