diff --git a/config/config.go b/config/config.go
index 17adf75..8cf094b 100644
--- a/config/config.go
+++ b/config/config.go
@@ -39,6 +39,8 @@ const CONFIGFILE_NAME = "amsterdam.yaml"
 // AmCLI is the command-line interface arguments structure.
 type AmCLI struct {
 	ConfigFile       string `arg:"-C,--config,env:AMSTERDAM_CONFIG" help:"Location of the configuration file."`
+	Debug            bool   `arg:"-D,--debug,env:AMSTERDAM_DEBUG" help:"Force Amsterdam to run in debug mode."`
+	Production       bool   `arg:"-P,--prod,--production,env:AMSTERDAM_PROD" help:"Force Amsterdam to run in production mode."`
 	DebugPanic       bool   `arg:"--debug-panic" help:"Development Only - disable Echo panic recovery"`
 	BuggyAttachments bool   `arg:"--buggy-attachments" help:"Some attachments may be buggy - truncate data if necessary"`
 }
@@ -59,9 +61,10 @@ func (*AmCLI) Version() string {
 // AmConfig holds the configuration of the application as read from YAML.
 type AmConfig struct {
 	Site struct {
-		BaseURL  string `yaml:"baseURL"`
-		Title    string `yaml:"title"`
-		SiteIcon struct {
+		Production bool   `yaml:"production"`
+		BaseURL    string `yaml:"baseURL"`
+		Title      string `yaml:"title"`
+		SiteIcon   struct {
 			Path string `yaml:"path"`
 			Type string `yaml:"type"`
 		} `yaml:"siteIcon"`
@@ -148,6 +151,7 @@ type AmConfig struct {
 
 // AmConfigComputed is the configuration values which are "computed" based only on values in AmConfig.
 type AmConfigComputed struct {
+	DebugMode        bool            // are we in debug mode?
 	UploadMaxSize    int32           // maximum upload size in bytes
 	UploadNoCompress map[string]bool // which upload types are not compressed?
 }
@@ -214,15 +218,16 @@ func overlayStructValue(dest, loaded, defaults reflect.Value) {
 		} else if fldDest.Kind() == reflect.Array || fldDest.Kind() == reflect.Slice {
 			// array of strings - merge the two arrays
 			m := make(map[string]bool)
+			rc := make([]string, 0, fldDefaults.Len()+fldLoaded.Len())
 			for i := 0; i < fldDefaults.Len(); i++ {
 				m[fldDefaults.Index(i).String()] = true
+				rc = append(rc, fldDefaults.Index(i).String())
 			}
 			for i := 0; i < fldLoaded.Len(); i++ {
-				m[fldLoaded.Index(i).String()] = true
-			}
-			rc := make([]string, 0, len(m))
-			for s := range m {
-				rc = append(rc, s)
+				if !m[fldLoaded.Index(i).String()] {
+					m[fldLoaded.Index(i).String()] = true
+					rc = append(rc, fldLoaded.Index(i).String())
+				}
 			}
 			fldDest.Set(reflect.ValueOf(rc))
 		} else if fldDest.Kind() == reflect.Bool {
@@ -320,6 +325,13 @@ func SetupConfig() {
 	}
 
 	// Compute additional values.
+	if CommandLine.Debug {
+		GlobalComputedConfig.DebugMode = true
+	} else if CommandLine.Production {
+		GlobalComputedConfig.DebugMode = false
+	} else {
+		GlobalComputedConfig.DebugMode = !GlobalConfig.Site.Production
+	}
 	tmp, err := parseDataSize(GlobalConfig.Posting.Uploads.MaxSize)
 	if err != nil {
 		panic(err.Error())
diff --git a/config/default.yaml b/config/default.yaml
index 888a0ff..bef3d74 100644
--- a/config/default.yaml
+++ b/config/default.yaml
@@ -7,6 +7,7 @@
 # file, You can obtain one at https://mozilla.org/MPL/2.0/.
 #
 site:
+  production: false
   baseURL: "http://localhost:1323"
   title: "Amsterdam Web Communities System"
   siteIcon:
diff --git a/email/sender.go b/email/sender.go
index cd17a21..dcba50c 100644
--- a/email/sender.go
+++ b/email/sender.go
@@ -228,7 +228,7 @@ func SetupMailSender() func() {
 	templateLoaders = append(templateLoaders, embedfs.NewLoader("templates/", emailTemplates))
 
 	// Initialize the template engine.
-	emailRenderer = jet.NewSet(multi.NewLoader(templateLoaders...), jet.DevelopmentMode(true))
+	emailRenderer = jet.NewSet(multi.NewLoader(templateLoaders...), jet.DevelopmentMode(config.GlobalComputedConfig.DebugMode))
 	emailRenderer.AddGlobal("AmsterdamVersion", config.AMSTERDAM_VERSION)
 	emailRenderer.AddGlobal("AmsterdamCopyright", config.AMSTERDAM_COPYRIGHT)
 	emailRenderer.AddGlobal("GlobalConfig", config.GlobalConfig)
diff --git a/ui/render_wrap.go b/ui/render_wrap.go
index ebaba3b..ab3ae18 100644
--- a/ui/render_wrap.go
+++ b/ui/render_wrap.go
@@ -16,6 +16,7 @@ import (
 	"net/http"
 	"time"
 
+	"git.erbosoft.com/amy/amsterdam/config"
 	"git.erbosoft.com/amy/amsterdam/database"
 	"github.com/klauspost/lctime"
 	"github.com/labstack/echo/v4"
@@ -141,6 +142,7 @@ func AmSendPageData(ctxt echo.Context, amctxt AmContext, command string, data an
 			}
 		}
 		amctxt.VarMap().Set("__bannerad", ad)
+		amctxt.VarMap().Set("__debugMode", config.GlobalComputedConfig.DebugMode)
 		if tmp := amctxt.GetScratch("frame_suppressLogin"); tmp != nil {
 			amctxt.VarMap().Set("__suppressLogin", true)
 		}
diff --git a/ui/templates.go b/ui/templates.go
index ebce38f..404ce69 100644
--- a/ui/templates.go
+++ b/ui/templates.go
@@ -302,7 +302,7 @@ func setupTemplates() {
 	templateLoaders = append(templateLoaders, embedfs.NewLoader("views/", static_views))
 
 	// Create the template renderer and add our globals to it.
-	views = jet.NewSet(multi.NewLoader(templateLoaders...), jet.DevelopmentMode(true))
+	views = jet.NewSet(multi.NewLoader(templateLoaders...), jet.DevelopmentMode(config.GlobalComputedConfig.DebugMode))
 	views.AddGlobal("AmsterdamVersion", config.AMSTERDAM_VERSION)
 	views.AddGlobal("AmsterdamCopyright", config.AMSTERDAM_COPYRIGHT)
 	views.AddGlobal("GlobalConfig", config.GlobalConfig)
diff --git a/ui/views/frame.jet b/ui/views/frame.jet
index f0057ad..a5667a2 100644
--- a/ui/views/frame.jet
+++ b/ui/views/frame.jet
@@ -18,7 +18,12 @@
     {{ range k, v := .FrameMetadata(0) }}
         <meta http-equiv="{{ k }}" content="{{ v }}">
     {{ end }}
-    <script src="https://cdn.tailwindcss.com"></script>
+    {{ if __debugMode }}
+        <script src="https://cdn.tailwindcss.com"></script>
+    {{ else }}
+        {* TODO - replace with reference to generated Tailwind CSS file *}
+        <script src="https://cdn.tailwindcss.com"></script>
+    {{ end }}
     <link rel="stylesheet" href="/static/css/ams_style.css" />
 </head>