[Python] How can I use base.html like a regular template, and render to it

I have my navbar css in my base.html, and then use {% extend base.html %} to add it into my regular template. However, I want to have a login/register option in my navbar (which is in my base.html), and I want to use cookies to decide whether to put login or register in the navbar. How can I have base.html be able to request cookies, when it doesn't have a view? Also, not every webpage on my site has a view, some are a plain html with {% extend base.html %}.

my base.html:

<!-- Global site tag (gtag.js) - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=UA-175481126-1"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());

gtag('config', 'UA-175481126-1');
</script>

<style>
ul {
list-style-type: none;
margin: 0;
padding: 0;
overflow: hidden;
font-family: Tahoma, Geneva, sans-serif;
background-color: #333;
}
li {
float: left;
border-right: 1px solid #bbb;
}
li a {
display: block;
color: white;
text-align: center;
padding: 14px 16px;
text-decoration: none;
}
/* Change the link color to #111 (black) on hover */
li a:hover {
background-color: #111;
color: white;
text-decoration:none;
}

/* for buttons*/
.paging {
background-color: #333;
border: none;
color: white;
padding: 8px 14px;
text-align: center;
text-decoration: none;
display: inline-block;
font-size: 16px;
font-family: Tahoma, Geneva, sans-serif;
}
button:hover {
background-color: #111;
}

.register {
float: right;
}

.paging {
background-color: #333;
border: none;
color: white;
padding: 8px 14px;
text-align: center;
text-decoration: none;
display: inline-block;
font-size: 16px;
font-family: Tahoma, Geneva, sans-serif;
}
button:hover {
background-color: #111;
}

/* title */

.title {
color: black;
padding: 10px;
text-align: center;
font-size: 40px;
font-family: Tahoma, Geneva, sans-serif;
Color: black;
text-decoration: none;
}

/* descriptions */

.description {
color: black;
padding: 15px;
font-family: Tahoma, Geneva, sans-serif;
text-align: left;
font-size: 13px;
}

/* embedd url */
.iframe-container{
position: relative;
width: 100%;
padding-bottom: 56.25%;
height: 0;
margin-left: auto; /* Automatic margin from left */
margin-right: auto; /* Automatic margin from right */
}
.iframe-container iframe{
position: absolute;
top:0;
left: 0;
width: 100%;
height: 100%;
}

/* make columns */

* {
box-sizing: border-box;
}

.row {
display: flex;
flex-direction: row;
flex-wrap: wrap;
flex: 0 0 100%;
max-width: 100%;
/* you can just remove these margins all together. Just wanted to emphasize that there should be no margin left or right, to avoid overflow */
margin-left: 0px;
margin-right: 0px;
}

.videos, .ads {
flex-grow: 0; flex-shrink: 0;
}

.ads {
display: block;
float: right;
background-color: #c1c4c9;
width: 25%;
}

.videos {
display: block;
float: left;
width: 75%;
padding-right: 10%;
padding-left: 10%;
}

.image {
padding-right: 5%;
padding-left: 5%;
padding-top: 5%;
padding-bottom: 5%;
}

.logo {
flex-direction:; row;
flex:; 0 0 100%;
max-width 100%;
justify-content:; center;
}

.banner {
/* float: left;*/
width: 100%;
height: 5%;
background-color: red;
color: white;
text-align: center;
}

img {
max-width: 100%;
max-height: 100%;
}

/* header */
.header {
background-color: #F1F1F1;
text-align: center;
padding: 20px;
font-family: Tahoma, Geneva, sans-serif;
}
</style>

<html>

{% load static %}

<link rel="shortcut icon" type="image/png" href="{% static 'images/favicon.ico' %}"/>

<div class="logo">
<div class="header">
<a href="/">
<img src="https://i.ibb.co/5Rqps7F/logo-black.png" alt="Computer Man">
</a>
</div>

<ul>
<li class="all"><a href="/">All videos</a></li>
<li class="stam"><a href="/stam">Stam videos</a></li>
<li class="music"><a href="/music">Music videos</a></li>
<li class="news"><a href="/news">News videos</a></li>
<li class="contact"><a href="/contact">Contact</a></li>
<li class="register"><a href="/register">Login/Register</a></li>
</ul>

<div class="banner">
<text align="center">We are still developing our site, so we may not be able to update videos as often as we want</text>
</div>
</div>

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">

<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>

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