Hello of course you can add some css, js ,and jquery. it'is possible to add some "static files" or simple add some css directly to you html template
like this ...if you want to add directly a css from a static file your html code will bes as something like this: (you need then to add your css file to "static/css/mystyle.css" and on the html page you need to add the classes where you need them...)
Code
<!DOCTYPE html>
{% load staticfiles %}
<html>
<head>
<meta charset="utf-8">
<title>How to add a css file to your DJANGO</title>
<link rel="stylesheet" href="{% static "css/mystyle.css" %}"/>
</head>
<body>
<h1> Hello ! this page use a little CSS. </h1>
<h2> for a nice view </h2>
</body>
</html>
You can also use bootstrapcdn if you want . Take a look at the "getbootstrap dot com", then look for bootstrapcdn at the "get started page" . then you may want to look for the different components you can use by clicking at "component " menu at top of the page. After you have clicked on component a new usefull menu will appear at the right side of the page
Hope it helps a little :)