use foreman

Procfile.dev

@@ -0,0 +1,2 @@
+web: env RUBY_DEBUG_OPEN=true bin/rails server
+css: yarn build:css --watch

bin/dev

@@ -1,2 +1,11 @@
-#!/usr/bin/env ruby
+#!/usr/bin/env sh
-exec "./bin/rails", "server", *ARGV
+
+if gem list --no-installed --exact --silent foreman; then
+  echo "Installing foreman..."
+  gem install foreman
+fi
+
+# Default to port 3000 if not specified
+export PORT="${PORT:-3000}"
+
+exec foreman start -f Procfile.dev --env /dev/null "$@"