diff --git a/lib/github-pages/configuration.rb b/lib/github-pages/configuration.rb
index ddcd0668..fa38a159 100644
--- a/lib/github-pages/configuration.rb
+++ b/lib/github-pages/configuration.rb
@@ -24,11 +24,12 @@ class Configuration
       },
     }.freeze
 
-    # Jekyll defaults merged with Pages defaults.
-    MERGED_DEFAULTS = Jekyll::Utils.deep_merge_hashes(
-      Jekyll::Configuration::DEFAULTS,
-      DEFAULTS
-    ).freeze
+    # User-overwritable defaults used only in production for practical reasons
+    PRODUCTION_DEFAULTS = Jekyll::Utils.deep_merge_hashes DEFAULTS, {
+      "sass" => {
+        "style" => "compressed",
+      },
+    }.freeze
 
     # Options which GitHub Pages sets, regardless of the user-specified value
     #
@@ -82,6 +83,11 @@ def development?
         Jekyll.env == "development"
       end
 
+      def defaults_for_env
+        defaults = development? ? DEFAULTS : PRODUCTION_DEFAULTS
+        Jekyll::Utils.deep_merge_hashes Jekyll::Configuration::DEFAULTS, defaults
+      end
+
       # Given a user's config, determines the effective configuration by building a user
       # configuration sandwhich with our overrides overriding the user's specified
       # values which themselves override our defaults.
@@ -91,7 +97,7 @@ def development?
       # Note: this is a highly modified version of Jekyll#configuration
       def effective_config(user_config)
         # Merge user config into defaults
-        config = Jekyll::Utils.deep_merge_hashes(MERGED_DEFAULTS, user_config)
+        config = Jekyll::Utils.deep_merge_hashes(defaults_for_env, user_config)
           .fix_common_issues
           .add_default_collections
 
diff --git a/spec/github-pages/configuration_spec.rb b/spec/github-pages/configuration_spec.rb
index 060a7319..72c9dcdc 100644
--- a/spec/github-pages/configuration_spec.rb
+++ b/spec/github-pages/configuration_spec.rb
@@ -14,6 +14,8 @@
   let(:configuration) { Jekyll.configuration(test_config) }
   let(:site)          { Jekyll::Site.new(configuration) }
   let(:effective_config) { described_class.effective_config(site.config) }
+  let(:defaults_for_env) { described_class.defaults_for_env }
+
   before(:each) do
     ENV.delete("DISABLE_WHITELIST")
     ENV["JEKYLL_ENV"] = "test"
@@ -55,6 +57,15 @@
     it "accepts local configs" do
       expect(effective_config["testing"]).to eql("123")
     end
+
+    context "in development" do
+      before { ENV["JEKYLL_ENV"] = "development" }
+
+      it "doesn't compress sass" do
+        expect(effective_config["sass"]).to be_nil
+        expect(defaults_for_env["sass"]).to be_nil
+      end
+    end
   end
 
   context "#set being called via the hook" do
@@ -159,6 +170,11 @@
           expect(described_class.disable_whitelist?).to eql(false)
         end
       end
+
+      it "compresses sass" do
+        expect(effective_config["sass"]).to eql("style" => "compressed")
+        expect(defaults_for_env["sass"]).to eql("style" => "compressed")
+      end
     end
   end
 end