This is the only diff remaining when I ran a brand new rails app through `standardrb --fix` for the first time.

standard_on_rails.diff

diff --git a/config/environments/development.rb b/config/environments/development.rb
index 87ec21e..9f34f1b 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -53,7 +53,6 @@ Rails.application.configure do
   # Highlight code that triggered database queries in logs.
   config.active_record.verbose_query_logs = true
 
-
   # Raises error for missing translations.
   # config.i18n.raise_on_missing_translations = true
 
diff --git a/config/environments/production.rb b/config/environments/production.rb
index 0fa6017..6192ed2 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -13,7 +13,7 @@ Rails.application.configure do
   config.eager_load = true
 
   # Full error reports are disabled and caching is turned on.
-  config.consider_all_requests_local       = false
+  config.consider_all_requests_local = false
   config.action_controller.perform_caching = true
 
   # Ensures that a master key has been made available in either ENV["RAILS_MASTER_KEY"]
@@ -44,7 +44,7 @@ Rails.application.configure do
   config.log_level = :info
 
   # Prepend all log lines with the following tags.
-  config.log_tags = [ :request_id ]
+  config.log_tags = [:request_id]
 
   # Use a different cache store in production.
   # config.cache_store = :mem_cache_store
@@ -74,9 +74,9 @@ Rails.application.configure do
   # config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new "app-name")
 
   if ENV["RAILS_LOG_TO_STDOUT"].present?
-    logger           = ActiveSupport::Logger.new(STDOUT)
+    logger = ActiveSupport::Logger.new($stdout)
     logger.formatter = config.log_formatter
-    config.logger    = ActiveSupport::TaggedLogging.new(logger)
+    config.logger = ActiveSupport::TaggedLogging.new(logger)
   end
 
   # Do not dump schema after migrations.
diff --git a/config/environments/test.rb b/config/environments/test.rb
index e57c036..eedff86 100644
--- a/config/environments/test.rb
+++ b/config/environments/test.rb
@@ -23,7 +23,7 @@ Rails.application.configure do
   }
 
   # Show full error reports and disable caching.
-  config.consider_all_requests_local       = true
+  config.consider_all_requests_local = true
   config.action_controller.perform_caching = false
   config.cache_store = :null_store
 
diff --git a/config/puma.rb b/config/puma.rb
index daaf036..ce4878f 100644
--- a/config/puma.rb
+++ b/config/puma.rb
@@ -4,7 +4,7 @@
 # the maximum value specified for Puma. Default is set to 5 threads for minimum
 # and maximum; this matches the default thread size of Active Record.
 #
-max_threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }
+max_threads_count = ENV.fetch("RAILS_MAX_THREADS", 5)
 min_threads_count = ENV.fetch("RAILS_MIN_THREADS") { max_threads_count }
 threads min_threads_count, max_threads_count
 
@@ -15,7 +15,7 @@ worker_timeout 3600 if ENV.fetch("RAILS_ENV", "development") == "development"
 
 # Specifies the `port` that Puma will listen on to receive requests; default is 3000.
 #
-port ENV.fetch("PORT") { 3000 }
+port ENV.fetch("PORT", 3000)
 
 # Specifies the `environment` that Puma will run in.
 #