Add CSS to iFrame [duplicate]
Solution 1:
Based on solution You've already found How to apply CSS to iframe?:
var cssLink = document.createElement("link")
cssLink.href = "file://path/to/style.css";
cssLink .rel = "stylesheet";
cssLink .type = "text/css";
frames['iframe'].document.body.appendChild(cssLink);
or more jqueryish (from Append a stylesheet to an iframe with jQuery):
var $head = $("iframe").contents().find("head");
$head.append($("<link/>",
{ rel: "stylesheet", href: "file://path/to/style.css", type: "text/css" }));
as for security issues: Disabling same-origin policy in Safari