Firefox extension content script does not load and append HTML

Everything below works in a Chrome extension but silently fails when ported to Firefox on:

1. loading the test.html unless I remove <style></style> from it
2. appending the #test_element to the body

Do styles have to go into a separate file for Firefox extension? Why does append() fail?

test.js

$(document).ready(function() {
    $.get(chrome.extension.getURL('/html/test.html'), function(data) {
        // not called unless style element is removed from HTML
        // and never actually appended if it is removed
        $(document.body).append($.parseHTML(data));
    });
});

test.html

<style></style>
<div id="test_element">
    <p>my name is cow</p>
</div>

manifest.json

{
    "manifest_version": 2,
    "name": "Test",
    "version": "1.0",

    "icons": {
        "64": "icons/icon-64.png"
    },

    "permissions": [
        "tabs",
        "storage",
        "idle"
    ],

    "content_scripts": [
        {
            "matches": ["<all_urls>"],
            "js": ["lib/jquery.js", "src/test.js"]
        }
    ],

    "web_accessible_resources": [
        "html/test.html"
    ]
}