diff --git a/mamweb/settings_common.py b/mamweb/settings_common.py
index ac161a16..802b7bb9 100644
--- a/mamweb/settings_common.py
+++ b/mamweb/settings_common.py
@@ -1,68 +1,56 @@
-"""
-Django settings for mamweb project.
-
-For more information on this file, see
-https://docs.djangoproject.com/en/1.7/topics/settings/
-
-For the full list of settings and their values, see
-https://docs.djangoproject.com/en/1.7/ref/settings/
-"""
-
-# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
 import os
 import traceback
 
 BASE_DIR = os.path.dirname(os.path.dirname(__file__))
 
 # Application definition
-
 SITE_ID = 1
 ROOT_URLCONF = 'mamweb.urls'
 WSGI_APPLICATION = 'mamweb.wsgi.application'
 
-APPEND_SLASH = True
-
-# Internationalization
-# https://docs.djangoproject.com/en/1.7/topics/i18n/
-
+# Lokalizace
 LANGUAGE_CODE = 'cs'
 TIME_ZONE = 'Europe/Prague'
-USE_I18N = True
-USE_L10N = True
-USE_TZ = True
-
-# Static files (CSS, JavaScript, Images)
-# https://docs.djangoproject.com/en/1.7/howto/static-files/
+USE_L10N = True  # S přechodem k djangu>=4 lze smazat (localized formatting)
+USE_TZ = True  # S přechodem k djangu>=5 lze smazat (timezone aware datetimes)
 
+# Statické soubory (CSS, JavaScript, obrázky) a další média
 STATIC_URL = '/static/'
 MEDIA_URL = '/media/'
 MEDIA_ROOT = os.path.join(BASE_DIR, 'media')
 STATIC_ROOT = os.path.join(BASE_DIR, 'static')
-
 STATICFILES_FINDERS = (
 	'django.contrib.staticfiles.finders.AppDirectoriesFinder',
 	'django.contrib.staticfiles.finders.FileSystemFinder',
 )
 
-# Where redirect for login required services
+# URL pro přihlášení (default je account/login)
 LOGIN_URL = 'login'
 LOGIN_REDIRECT_URL = 'profil'
 
+
 # Odhlášení po zavření prohlížeče
 # (pozor nefunguje na firefox se znovuotevíráním oken po startu firefoxu)
 # default je False a SESSION_COOKIE_AGE = 3600*24*14 = 2 týdny
 SESSION_EXPIRE_AT_BROWSER_CLOSE = True
 DOBA_ODHLASENI_PRI_ZASKRTNUTI_NEODHLASOVAT = 365 * 24 * 3600  # rok
 
-# Modules configuration
 
+# SECURITY WARNING: keep the secret key used in production secret!
+# Create file 'django.secret' in every install (it is not kept in git)
+try:
+	with open(os.path.join(os.path.dirname(__file__), '..', 'django.secret')) as f:
+		SECRET_KEY = f.readline().strip()
+except:
+	SECRET_KEY = '12345zmr_k53a*@f4q_+ji^o@!pgpef*5&8c7zzdqwkdlkj'
+
+
+# Přidávání dalších součástí (do) djangovské mašinérie
 AUTHENTICATION_BACKENDS = (
 	'django.contrib.auth.backends.ModelBackend',
 )
-
-
 MIDDLEWARE = (
-#    'reversion.middleware.RevisionMiddleware',
+	# 'reversion.middleware.RevisionMiddleware',
 	'django.contrib.sessions.middleware.SessionMiddleware',
 	'django.middleware.common.CommonMiddleware',
 	'django.middleware.csrf.CsrfViewMiddleware',
@@ -71,7 +59,6 @@ MIDDLEWARE = (
 	'django.middleware.clickjacking.XFrameOptionsMiddleware',
 	'django.contrib.flatpages.middleware.FlatpageFallbackMiddleware',
 )
-
 TEMPLATES = [
 	{
 		'BACKEND': 'django.template.backends.django.DjangoTemplates',
@@ -80,7 +67,7 @@ TEMPLATES = [
 		'OPTIONS': {
 			'context_processors': (
 				'django.contrib.auth.context_processors.auth',
-		'django.template.context_processors.request',
+				'django.template.context_processors.request',
 				'django.contrib.messages.context_processors.messages',
 				'sekizai.context_processors.sekizai',
 				'header_fotky.context_processors.vzhled',
@@ -90,12 +77,7 @@ TEMPLATES = [
 		},
 	},
 ]
-
-
-
 INSTALLED_APPS = (
-
-
 	# Basic
 	'django.contrib.contenttypes',
 	'django.contrib.sessions',
@@ -151,59 +133,50 @@ INSTALLED_APPS = (
 
 	# Admin upravy:
 
-#    'material',
-#    'material.admin',
-#    'admin_tools',
-#    'admin_tools.theming',
-#    'admin_tools.menu',
-#    'admin_tools.dashboard',
+	# 'material',
+	# 'material.admin',
+	# 'admin_tools',
+	# 'admin_tools.theming',
+	# 'admin_tools.menu',
+	# 'admin_tools.dashboard',
 	'django.contrib.admin',
 
 	# Nechat na konci (INSTALLED_APPS je uspořádané):
 	'django_cleanup.apps.CleanupConfig',  # Uklízí media/
 )
 
-DEBUG_TOOLBAR_CONFIG = {
-	'SHOW_COLLAPSED': True,
-}
 
-SUMMERNOTE_CONFIG = {
-	'iframe': False,
-	'airMode': False,
-	'attachment_require_authentication': True,
-	'width': '80%',
-#    'height': '30em',
-	'toolbar': [
-		['style', ['style']],
-		['font', ['bold', 'italic', 'superscript', 'subscript', 'clear']],
-		['color', ['color']],
-		['para', ['ul', 'ol', 'paragraph']],
-		['table', ['table']],
-		['insert', ['link', 'picture', 'hr']],
-		['view', ['fullscreen', 'codeview']],
-		['help', ['help']],
-	 ]
-}
+# MaM-specifické složky
+SEMINAR_RESENI_DIR = os.path.join('reseni')
+SEMINAR_KONFERY_DIR = os.path.join('konfery')
+KOREKTURY_PDF_DIR = os.path.join('korektury', 'pdf')
+KOREKTURY_IMG_DIR = os.path.join('korektury', 'img')
+CISLO_IMG_DIR = os.path.join('cislo', 'img')
 
+
+# MaM-specifické konstanty
+# TODO (e-maily atd.)
+
+
+# CKEditor = WYSIWYG html editor
 CKEDITOR_UPLOAD_PATH = "uploads/"
 CKEDITOR_IMAGE_BACKEND = 'pillow'
-#CKEDITOR_JQUERY_URL = '//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js'
+# CKEDITOR_JQUERY_URL = '//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js'
 CKEDITOR_CONFIGS = {
 	'default': {
 		'entities': False,
 		'toolbar': [
 			['Source', 'ShowBlocks', '-', 'Maximize'],
 			['Bold', 'Italic', 'Subscript', 'Superscript', '-', 'RemoveFormat'],
-			['NumberedList','BulletedList','-','Blockquote','-','JustifyLeft','JustifyCenter','JustifyRight','JustifyBlock'],
+			['NumberedList', 'BulletedList', '-', 'Blockquote', '-', 'JustifyLeft', 'JustifyCenter', 'JustifyRight', 'JustifyBlock'],
 			['Link', 'Unlink', 'Anchor', '-', 'Image', 'Table', 'HorizontalRule'],
 			['Format'],
-
 		],
-#        'toolbar': 'full',
+		# 'toolbar': 'full',
 		'height': '40em',
 		'width': '100%',
 		'toolbarStartupExpanded': False,
-		'allowedContent' : True,
+		'allowedContent': True,
 	},
 }
 
@@ -223,31 +196,21 @@ WEBPACK_LOADER = {
 
 
 # Dajngo REST Framework
-
 REST_FRAMEWORK = {
 	'DEFAULT_PAGINATION_CLASS': 'rest_framework.pagination.LimitOffsetPagination',
 	'PAGE_SIZE': 100
 }
 
 
-# SECURITY WARNING: keep the secret key used in production secret!
-# Create file 'django.secret' in every install (it is not kept in git)
-
-try:
-	with open(os.path.join(os.path.dirname(__file__), '..', 'django.secret')) as f:
-		SECRET_KEY = f.readline().strip()
-except:
-	SECRET_KEY = '12345zmr_k53a*@f4q_+ji^o@!pgpef*5&8c7zzdqwkdlkj'
-
-# Logging
-
+# Logování
 LOGGING = {
 		'version': 1,
 		'disable_existing_loggers': False,
 
 		'formatters': { 
 			'verbose': { 
-				'format': '%(levelname)s %(asctime)s %(module)s (logger %(name)s): %(message)s' 
+				'format':
+					'%(levelname)s %(asctime)s %(module)s (logger %(name)s): %(message)s'
 				}, 
 			}, 
 
@@ -278,18 +241,18 @@ LOGGING = {
 				'filters': ['Http404AsInfo'],
 				},
 
-			'seminar.prihlaska.form':{
-		'handlers': ['console','registration_logfile'],
-		'level': 'INFO'
-		},
-			'seminar.prihlaska.problem':{
-		'handlers': ['console','mail_registration','registration_error_log'],
-		'level': 'INFO'
-		},
+			'seminar.prihlaska.form': {
+				'handlers': ['console', 'registration_logfile'],
+				'level': 'INFO'
+				},
+			'seminar.prihlaska.problem': {
+				'handlers': ['console', 'mail_registration', 'registration_error_log'],
+				'level': 'INFO'
+				},
 
 			# Catch-all logger
 			'': {
-				'handlers': ['console'], # Add 'mail_admins' in prod and test
+				'handlers': ['console'],
 				'level': 'DEBUG',
 				'filters': ['StripSensitiveFormData'],
 				},
@@ -299,7 +262,7 @@ LOGGING = {
 		'handlers': {
 
 			'console': {
-				'level': 'WARNING', ## Set to 'DEBUG' in local
+				'level': 'WARNING',
 				'class': 'logging.StreamHandler',
 				'formatter': 'verbose', 
 				},
@@ -315,36 +278,24 @@ LOGGING = {
 				'class': 'django.utils.log.AdminEmailHandler',
 				'formatter': 'verbose', 
 				},
-			'registration_logfile':{
+			'registration_logfile': {
 				'level': 'INFO',
-		'class': 'logging.FileHandler',
-		# filename declared in specific configuration files
-				'formatter': 'verbose', 
-		},
-		'registration_error_log':{
+				'class': 'logging.FileHandler',
+				# filename declared in specific configuration files
+				'formatter': 'verbose',
+				},
+			'registration_error_log': {
 				'level': 'INFO',
-		'class': 'logging.FileHandler',
-		# filename declared in specific configuration files
+				'class': 'logging.FileHandler',
+				# filename declared in specific configuration files
 				'formatter': 'verbose', 
-		},
-		
+				},
+
 			},
 		}
 
-# Permissions for uploads
-FILE_UPLOAD_PERMISSIONS = 0o0644
-
-# MaM specific
 
-SEMINAR_RESENI_DIR = os.path.join('reseni')
-SEMINAR_KONFERY_DIR = os.path.join('konfery')
-KOREKTURY_PDF_DIR = os.path.join('korektury', 'pdf')
-KOREKTURY_IMG_DIR = os.path.join('korektury', 'img')
-CISLO_IMG_DIR = os.path.join('cislo', 'img')
-
-
-
-# Logování chyb
+# Logování neexistujících proměnných v templatech
 class InvalidTemplateVariable(str):
 	def __mod__(self, variable):
 		import logging
@@ -356,5 +307,38 @@ class InvalidTemplateVariable(str):
 		return ''
 TEMPLATES[0]['OPTIONS']['string_if_invalid'] = InvalidTemplateVariable('%s')
 
+
 # Django 3.2 vyžaduje explicitní nastavení autoklíče, zatím nechápu proč
 DEFAULT_AUTO_FIELD = 'django.db.models.AutoField'
+
+
+# TODO odstranit? (Je to default.)
+# Whether to append trailing slashes to URLs.
+APPEND_SLASH = True
+# TODO odstranit? (Je to default.)
+# Permissions for uploads
+FILE_UPLOAD_PERMISSIONS = 0o0644
+# TODO odstranit? (Je to default.)
+# Automatická lokalizace
+USE_I18N = True
+
+
+# TODO odstranit? (Nevím o tom, že bychom ho někde používali.)
+# Summernote = WYSIWYG editor (pro admin?)
+SUMMERNOTE_CONFIG = {
+	'iframe': False,
+	'airMode': False,
+	'attachment_require_authentication': True,
+	'width': '80%',
+	# 'height': '30em',
+	'toolbar': [
+		['style', ['style']],
+		['font', ['bold', 'italic', 'superscript', 'subscript', 'clear']],
+		['color', ['color']],
+		['para', ['ul', 'ol', 'paragraph']],
+		['table', ['table']],
+		['insert', ['link', 'picture', 'hr']],
+		['view', ['fullscreen', 'codeview']],
+		['help', ['help']],
+	]
+}
diff --git a/mamweb/settings_common_debug.py b/mamweb/settings_common_debug.py
new file mode 100644
index 00000000..81caa5c6
--- /dev/null
+++ b/mamweb/settings_common_debug.py
@@ -0,0 +1,22 @@
+from .settings_common import *
+
+DEBUG = True
+TEMPLATES[0]['OPTIONS']['debug'] = True
+
+MIDDLEWARE += (
+	'debug_toolbar.middleware.DebugToolbarMiddleware',
+)
+
+INSTALLED_APPS += (
+	'debug_toolbar',  # Takovéto užitečné (pro debug) na html stránce vpravo
+	'django_extensions',  # Kolekce zajímavých ./manage.py commandů
+)
+
+DEBUG_TOOLBAR_CONFIG = {
+	'SHOW_COLLAPSED': True,
+}
+
+# Nechceme nikomu omylem poslat e-mail
+# Když někdo spustí omylem tohle nastavení, prostě to při poslání mailu spadne
+# V settings_local a settings_test přepíšeme...
+EMAIL_BACKEND = None
diff --git a/mamweb/settings_local.py b/mamweb/settings_local.py
index cb992015..4fd970d0 100644
--- a/mamweb/settings_local.py
+++ b/mamweb/settings_local.py
@@ -1,5 +1,3 @@
-import os.path
-
 #
 # Lokalni / vyvojove nastaveni settings.py
 #
@@ -7,35 +5,20 @@ import os.path
 # DJANGO_SETTINGS_MODULE=mamweb.settings_local ./manage.py ...
 #
 
-# Import common settings
-from .settings_common import *
-
-MIDDLEWARE += (
-	'debug_toolbar.middleware.DebugToolbarMiddleware',
-	)
+import os.path
+from ipaddress import ip_network
 
-# Quick-start development settings - unsuitable for production
-# See https://docs.djangoproject.com/en/1.7/howto/deployment/checklist/
+from .settings_common_debug import *
+LOCAL_TEST_PROD = "local"
 
-INSTALLED_APPS += (
-	'debug_toolbar',
-	'django_extensions',
-	)
 
-# SECURITY WARNING: don't run with debug turned on in production!
-DEBUG = True
 INTERNAL_IPS = ['127.0.0.1']
-
-TEMPLATES[0]['OPTIONS']['debug'] = True
-
-from ipaddress import ip_network
 ALLOWED_HOSTS = [str(ip) for ip in ip_network('192.168.0.0/16')]
-ALLOWED_HOSTS.append('127.0.0.1')
-ALLOWED_HOSTS.append('localhost')
+ALLOWED_HOSTS += ['127.0.0.1', 'localhost']
 
-# Database
-# https://docs.djangoproject.com/en/1.7/ref/settings/#databases
 
+# Databáze
+# SQLite
 DATABASES = {
 	'default': {
 		'ENGINE': 'django.db.backends.sqlite3',
@@ -45,15 +28,21 @@ DATABASES = {
 			},
 	},
 }
-#DATABASES = {
-#    'default': {
-#        'ENGINE': 'django.db.backends.postgresql_psycopg2',
-#        'NAME': 'mam_local',
-#        'USER': 'mam',
-#    },
-#}
+# # PostgreSQL
+# DATABASES = {
+# 	'default': {
+# 		'ENGINE': 'django.db.backends.postgresql_psycopg2',
+# 		'NAME': 'mam_local',
+# 		'USER': 'mam',
+# 	},
+# }
+
 
-# LOGGING
+# E-maily posílat chceme, ale do terminálu :-)
+EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'
+
+
+# Logování
 LOGGING = {
 	'version': 1,
 	'disable_existing_loggers': True,
@@ -78,12 +67,6 @@ LOGGING = {
 		},
 	},
 	'loggers': {
-	 # Vypisovani databazovych dotazu do konzole
-		 #'django.db.backends': {
-		 #    'level': 'DEBUG',
-		 #    'handlers': ['console'],
-		 #    'propagate': False,
-		 #},
 		'werkzeug': {
 			'handlers': ['console'],
 			'level': 'DEBUG',
@@ -96,11 +79,3 @@ LOGGING = {
 		},
 	},
 }
-
-# set to 'DEBUG' for EXTRA verbose output
-# LOGGING['handlers']['console']['level'] = 'INFO'
-
-# E-maily posílat chceme, ale do terminálu :-)
-EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'
-
-LOCAL_TEST_PROD = "local"
diff --git a/mamweb/settings_prod.py b/mamweb/settings_prod.py
index 22aac97c..ca340dc2 100644
--- a/mamweb/settings_prod.py
+++ b/mamweb/settings_prod.py
@@ -1,6 +1,3 @@
-
-import os.path
-
 #
 # Produkcni nastaveni settings.py
 #
@@ -10,27 +7,27 @@ import os.path
 
 # Import common settings
 from .settings_common import *
+LOCAL_TEST_PROD = "prod"
 
 
-# See https://docs.djangoproject.com/en/1.7/howto/deployment/checklist/
-
-INSTALLED_APPS += (
-	'django_extensions',
-	)
-
-# SECURITY WARNING: keep the secret key used in production secret!
 assert not SECRET_KEY.startswith('12345')
-
 # SECURITY WARNING: don't run with debug turned on in production!
 DEBUG = False
-
 TEMPLATE_DEBUG = False
+# SECURITY: only send sensitive cookies via HTTPS
+SESSION_COOKIE_SECURE = True
+CSRF_COOKIE_SECURE = True
+
 
 ALLOWED_HOSTS = ['mam.mff.cuni.cz', 'www.mam.mff.cuni.cz', 'gimli.ms.mff.cuni.cz']
 
-# Database
-# https://docs.djangoproject.com/en/1.7/ref/settings/#databases
+# Přidání aplikací
+INSTALLED_APPS += (
+	'django_extensions',  # Kolekce zajímavých ./manage.py commandů
+	)
+
 
+# Databáze
 DATABASES = {
 	'default': {
 		'ENGINE': 'django.db.backends.postgresql_psycopg2',
@@ -42,25 +39,14 @@ DATABASES = {
 	},
 }
 
-import os
-
+# Nastavení e-mailů (odkud a kam mají chodit)
 SERVER_EMAIL = 'mamweb-prod-errors@mam.mff.cuni.cz'
 ADMINS = [('M&M ERRORs', 'mam-errors@mam.mff.cuni.cz')]
 
 
-# SECURITY: only send sensitive cookies via HTTPS
-
-SESSION_COOKIE_SECURE = True
-CSRF_COOKIE_SECURE = True
-
-
-
-# LOGGING 
-
+# Logování
 LOGGING['loggers']['']['handlers'] = ['console', 'mail_admins']
 LOGGING['loggers']['django']['handlers'] = ['console', 'mail_admins']
 LOGGING['loggers']['django.security.csrf']['level'] = 'ERROR'
 LOGGING['handlers']['registration_logfile']['filename'] = '/home/mam-web/logs/prod/registration.log'
 LOGGING['handlers']['registration_error_log']['filename'] = '/home/mam-web/logs/prod/registration_errors.log'
-
-LOCAL_TEST_PROD = "prod"
diff --git a/mamweb/settings_test.py b/mamweb/settings_test.py
index 6d394b04..1e9de7b5 100644
--- a/mamweb/settings_test.py
+++ b/mamweb/settings_test.py
@@ -1,6 +1,3 @@
-
-import os.path
-
 #
 # Testovaci nastaveni settings.py (testovani na mam-test.ks.marfyz.cz)
 #
@@ -8,34 +5,20 @@ import os.path
 # DJANGO_SETTINGS_MODULE=mamweb.settings_test ./manage.py ...
 #
 
-# Import common settings
-from .settings_common import * # zatim nutne, casem snad vyresime # noqa
-
-MIDDLEWARE += (
-	'debug_toolbar.middleware.DebugToolbarMiddleware',
-	)
-
-# Quick-start development settings - unsuitable for production
-# See https://docs.djangoproject.com/en/1.7/howto/deployment/checklist/
+from .settings_common_debug import *
+LOCAL_TEST_PROD = "test"
 
-INSTALLED_APPS += (
-	'debug_toolbar',
-	'django_extensions',
-	)
 
-# SECURITY WARNING: keep the secret key used in production secret!
 SECRET_KEY = ')^u=i65*zmr_k53a*@f4q_+ji^o@!pgpef*5&8c7zzv9l+zo)n'
+# SECURITY: only send sensitive cookies via HTTPS
+SESSION_COOKIE_SECURE = True
+CSRF_COOKIE_SECURE = True
 
-# SECURITY WARNING: don't run with debug turned on in production!
-DEBUG = True
-
-TEMPLATES[0]['OPTIONS']['debug'] = True
 
 ALLOWED_HOSTS = ['mam-test.kam.mff.cuni.cz', 'gimli.ms.mff.cuni.cz', 'mam-test.ks.matfyz.cz']
 
-# Database
-# https://docs.djangoproject.com/en/1.7/ref/settings/#databases
 
+# Databáze
 DATABASES = {
 	'default': {
 		'ENGINE': 'django.db.backends.postgresql_psycopg2',
@@ -47,31 +30,27 @@ DATABASES = {
 	},
 }
 
-import os
 
+# Nastavení e-mailů (odkud a kam mají chodit)
 SERVER_EMAIL = 'mamweb-test-errors@mam.mff.cuni.cz'
 ADMINS = [
 	('M&M ERRORs', 'mam-errors@mam.mff.cuni.cz'),
 ]
 
 
-# SECURITY: only send sensitive cookies via HTTPS
+# Testování e-mailů
+EMAIL_BACKEND = 'various.mail_prefixer.PrefixingMailBackend'
+# TODO Pouze na otestování testu… Zvolit konferu!
+# XXX: Je to pole, protože implementační detail backendu.
+TESTOVACI_EMAILOVA_KONFERENCE = ['betatest@mam.mff.cuni.cz']
 
-SESSION_COOKIE_SECURE = True
-CSRF_COOKIE_SECURE = True
 
-# LOGGING
+# Netuším proč (Jidáš)...
+FILE_UPLOAD_PERMISSIONS = 0o440
 
+
+# Logování
 LOGGING['loggers']['']['handlers'] = ['console', 'mail_admins']
 LOGGING['loggers']['django']['handlers'] = ['console', 'mail_admins']
 LOGGING['handlers']['registration_logfile']['filename'] = '/home/mam-web/logs/test/registration.log'
 LOGGING['handlers']['registration_error_log']['filename'] = '/home/mam-web/logs/test/registration_errors.log'
-
-FILE_UPLOAD_PERMISSIONS = 0o440
-
-# Testování e-mailů
-EMAIL_BACKEND = 'various.mail_prefixer.PrefixingMailBackend'
-# TODO Pouze na otestování testu… Zvolit konferu!
-# XXX: Je to pole, protože implementační detail backendu.
-TESTOVACI_EMAILOVA_KONFERENCE = ['betatest@mam.mff.cuni.cz']
-LOCAL_TEST_PROD = "test"