I am using javascript to inject a few DOM elements into the page. I am able to inject a single DOM element and apply CSS style to it:

var $e = $('<div id="header"></div>');
$('body').append($e);

$e.css({
    background: '#fbf7f7',
});

Problem: If I have nested elements within $e, how can I apply CSS styles to the parents and its children seperately?

var $e = $('<div id="header"><div class="header-content"><span class="title"></span></div></div>');