diff --git a/app/controllers/auth/confirmations_controller.rb b/app/controllers/auth/confirmations_controller.rb
index 7ca7be5f8e..bf5c84ccf4 100644
--- a/app/controllers/auth/confirmations_controller.rb
+++ b/app/controllers/auth/confirmations_controller.rb
@@ -5,7 +5,6 @@ class Auth::ConfirmationsController < Devise::ConfirmationsController
 
   layout 'auth'
 
-  before_action :set_body_classes
   before_action :set_confirmation_user!, only: [:show, :confirm_captcha]
   before_action :redirect_confirmed_user, if: :signed_in_confirmed_user?
 
@@ -73,10 +72,6 @@ class Auth::ConfirmationsController < Devise::ConfirmationsController
     user_signed_in? && current_user.confirmed? && current_user.unconfirmed_email.blank?
   end
 
-  def set_body_classes
-    @body_classes = 'lighter'
-  end
-
   def after_resending_confirmation_instructions_path_for(_resource_name)
     if user_signed_in?
       if current_user.confirmed? && current_user.approved?
diff --git a/app/controllers/auth/passwords_controller.rb b/app/controllers/auth/passwords_controller.rb
index de001f062b..7c1ff59671 100644
--- a/app/controllers/auth/passwords_controller.rb
+++ b/app/controllers/auth/passwords_controller.rb
@@ -3,7 +3,6 @@
 class Auth::PasswordsController < Devise::PasswordsController
   skip_before_action :check_self_destruct!
   before_action :redirect_invalid_reset_token, only: :edit, unless: :reset_password_token_is_valid?
-  before_action :set_body_classes
 
   layout 'auth'
 
@@ -24,10 +23,6 @@ class Auth::PasswordsController < Devise::PasswordsController
     redirect_to new_password_path(resource_name)
   end
 
-  def set_body_classes
-    @body_classes = 'lighter'
-  end
-
   def reset_password_token_is_valid?
     resource_class.with_reset_password_token(params[:reset_password_token]).present?
   end
diff --git a/app/controllers/auth/registrations_controller.rb b/app/controllers/auth/registrations_controller.rb
index e5a2ac0270..c12960934e 100644
--- a/app/controllers/auth/registrations_controller.rb
+++ b/app/controllers/auth/registrations_controller.rb
@@ -105,7 +105,7 @@ class Auth::RegistrationsController < Devise::RegistrationsController
   private
 
   def set_body_classes
-    @body_classes = %w(edit update).include?(action_name) ? 'admin' : 'lighter'
+    @body_classes = 'admin' if %w(edit update).include?(action_name)
   end
 
   def set_invite
diff --git a/app/controllers/auth/sessions_controller.rb b/app/controllers/auth/sessions_controller.rb
index 6ed7b2baac..6210e4dbf9 100644
--- a/app/controllers/auth/sessions_controller.rb
+++ b/app/controllers/auth/sessions_controller.rb
@@ -16,8 +16,6 @@ class Auth::SessionsController < Devise::SessionsController
 
   include Auth::TwoFactorAuthenticationConcern
 
-  before_action :set_body_classes
-
   content_security_policy only: :new do |p|
     p.form_action(false)
   end
@@ -103,10 +101,6 @@ class Auth::SessionsController < Devise::SessionsController
 
   private
 
-  def set_body_classes
-    @body_classes = 'lighter'
-  end
-
   def home_paths(resource)
     paths = [about_path, '/explore']
 
diff --git a/app/controllers/auth/setup_controller.rb b/app/controllers/auth/setup_controller.rb
index 40916d2887..ad872dc607 100644
--- a/app/controllers/auth/setup_controller.rb
+++ b/app/controllers/auth/setup_controller.rb
@@ -5,7 +5,6 @@ class Auth::SetupController < ApplicationController
 
   before_action :authenticate_user!
   before_action :require_unconfirmed_or_pending!
-  before_action :set_body_classes
   before_action :set_user
 
   skip_before_action :require_functional!
@@ -35,10 +34,6 @@ class Auth::SetupController < ApplicationController
     @user = current_user
   end
 
-  def set_body_classes
-    @body_classes = 'lighter'
-  end
-
   def user_params
     params.require(:user).permit(:email)
   end
diff --git a/app/controllers/concerns/auth/two_factor_authentication_concern.rb b/app/controllers/concerns/auth/two_factor_authentication_concern.rb
index 404164751a..0fb11428dc 100644
--- a/app/controllers/concerns/auth/two_factor_authentication_concern.rb
+++ b/app/controllers/concerns/auth/two_factor_authentication_concern.rb
@@ -83,7 +83,6 @@ module Auth::TwoFactorAuthenticationConcern
   def prompt_for_two_factor(user)
     register_attempt_in_session(user)
 
-    @body_classes     = 'lighter'
     @webauthn_enabled = user.webauthn_enabled?
     @scheme_type      = if user.webauthn_enabled? && user_params[:otp_attempt].blank?
                           'webauthn'
diff --git a/app/controllers/concerns/challengable_concern.rb b/app/controllers/concerns/challengable_concern.rb
index 09874fb405..c8d1a0bef7 100644
--- a/app/controllers/concerns/challengable_concern.rb
+++ b/app/controllers/concerns/challengable_concern.rb
@@ -42,7 +42,6 @@ module ChallengableConcern
   end
 
   def render_challenge
-    @body_classes = 'lighter'
     render 'auth/challenges/new', layout: 'auth'
   end
 
diff --git a/app/controllers/mail_subscriptions_controller.rb b/app/controllers/mail_subscriptions_controller.rb
index 1caeaaacf4..34df75f63a 100644
--- a/app/controllers/mail_subscriptions_controller.rb
+++ b/app/controllers/mail_subscriptions_controller.rb
@@ -5,7 +5,6 @@ class MailSubscriptionsController < ApplicationController
 
   skip_before_action :require_functional!
 
-  before_action :set_body_classes
   before_action :set_user
   before_action :set_type
 
@@ -25,10 +24,6 @@ class MailSubscriptionsController < ApplicationController
     not_found unless @user
   end
 
-  def set_body_classes
-    @body_classes = 'lighter'
-  end
-
   def set_type
     @type = email_type_from_param
   end
diff --git a/app/javascript/styles/mastodon/basics.scss b/app/javascript/styles/mastodon/basics.scss
index 456e042c53..1f961cb9e1 100644
--- a/app/javascript/styles/mastodon/basics.scss
+++ b/app/javascript/styles/mastodon/basics.scss
@@ -66,10 +66,6 @@ body {
     }
   }
 
-  &.lighter {
-    background: $ui-base-color;
-  }
-
   &.with-modals {
     overflow-x: hidden;
     overflow-y: scroll;
@@ -109,7 +105,6 @@ body {
   }
 
   &.embed {
-    background: lighten($ui-base-color, 4%);
     margin: 0;
     padding-bottom: 0;
 
@@ -122,15 +117,12 @@ body {
   }
 
   &.admin {
-    background: var(--background-color);
     padding: 0;
   }
 
   &.error {
     position: absolute;
     text-align: center;
-    color: $darker-text-color;
-    background: $ui-base-color;
     width: 100%;
     height: 100%;
     padding: 0;