Overriding admin css in django

I want to change certain css in admin django like base.css. Is it better to change directly in the django library? How can I override it in the best way?

It depends a lot of what you want to do. Though first of all: do not overwrite it in the Django admin directly. You got two options I think are reasonable:

1. If you want to change the appearance of the admin in general you should override admin templates. This is covered in details here: Overriding admin templates. Sometimes you can just extend the original admin file and then overwrite a block like {% block extrastyle %}{% endblock %} in django/contrib/admin/templates/admin/base.html as an example.
2. If your style is model specific you can add additional styles via the Media meta class in your admin.py. See an example here:

class MyModelAdmin(admin.ModelAdmin):
    class Media:
        js = ('js/admin/my_own_admin.js',)    
        css = {
             'all': ('css/admin/my_own_admin.css',)
        }

• In settings.py, make sure your app is listed before admin in the INSTALLED_APPS.
• Create (your-app)/templates/admin/base_site.html and put the <style> block into the {% block extrahead %}

Example:

{% extends "admin/base_site.html" %}
{% block extrahead %}
    <style>
        .field-__str__ {
            font-family: Consolas, monospace;
        }
    </style>
{% endblock %}

This solution will work for the admin site, I think it's the cleanest way because it overrides base_site.html which doesn't change when upgrading django.

Create in your templates directory a folder called admin in it create a file named base_site.html.

Create in your static directory under css a file called admin-extra.css .

Write in it all the custom css you want for your forms like: body{background: #000;}.

Paste this in the base_site.html:

{% extends "admin/base.html" %}
{% load static from staticfiles %} # This might be just {% load static %} in your ENV

{% block title %}{{ title }} | {{ site_title|default:_('Django site admin') }}{% endblock %}

{% block extrastyle %}{{ block.super }}<link rel="stylesheet" type="text/css" href="{% static "css/admin-extra.css" %}" />{% endblock %}

{% block branding %}
<h1 id="site-name"><a href="{% url 'admin:index' %}">{{ site_header|default:_('Django administration') }}</a></h1>
{% endblock %}

{% block nav-global %}{% endblock %}

As mentioned in the comments: make sure your app is before the admin app in INSTALLED_APPS, otherwise your template doesn't override django's

That's It! you're done

I just extended admin/base.html to include a reference to my own css file - at the end. The beauty of css is that you don't have to touch existing definitions, just re-define.