https://gitlab.com/mailman/hyperkitty/-/merge_requests/656

From 3961ea048f00da1004bbfe22f43ea2a494279d49 Mon Sep 17 00:00:00 2001
From: "Bernhard M. Wiedemann" <bwiedemann@suse.de>
Date: Mon, 16 Dec 2024 16:08:45 +0100
Subject: [PATCH] Use content based hashing

for deterministic .css files
Without this patch, the mode defaulted to `mtime`
and caused variations between builds.

Fixes #527

This patch was done while working on reproducible builds for openSUSE, sponsored by the NLnet NGI0 fund.

diff --git a/example_project/settings.py b/example_project/settings.py
index ec7f742..1c53df6 100644
--- a/build_static_files/settings.py
+++ b/build_static_files/settings.py
@@ -304,6 +304,7 @@ SOCIALACCOUNT_PROVIDERS = {
 # django-compressor
 # https://pypi.python.org/pypi/django_compressor
 #
+COMPRESS_CSS_HASHING_METHOD = 'content'
 COMPRESS_PRECOMPILERS = (
    ('text/x-scss', 'sassc -t compressed {infile} {outfile}'),
    ('text/x-sass', 'sassc -t compressed {infile} {outfile}'),