diff --git a/server/pages/flow-callback.go.html b/server/pages/flow-callback.go.html
index d114dd0..e9eb583 100644
--- a/server/pages/flow-callback.go.html
+++ b/server/pages/flow-callback.go.html
@@ -2,6 +2,7 @@
 <html lang="en">
 <head>
     <title>{{.ServiceName}}</title>
+    <link rel="stylesheet" href="/theme/style.css">
     <script>
         let loginData = {
             target:{{.TargetOrigin}},
diff --git a/server/pages/flow-popup-memory.go.html b/server/pages/flow-popup-memory.go.html
index 4661af7..47ea38f 100644
--- a/server/pages/flow-popup-memory.go.html
+++ b/server/pages/flow-popup-memory.go.html
@@ -2,6 +2,7 @@
 <html lang="en">
 <head>
     <title>{{.ServiceName}}</title>
+    <link rel="stylesheet" href="/theme/style.css">
 </head>
 <body>
 <header>
diff --git a/server/pages/flow-popup.go.html b/server/pages/flow-popup.go.html
index 86c67ca..a6c78ea 100644
--- a/server/pages/flow-popup.go.html
+++ b/server/pages/flow-popup.go.html
@@ -2,6 +2,7 @@
 <html lang="en">
 <head>
     <title>{{.ServiceName}}</title>
+    <link rel="stylesheet" href="/theme/style.css">
 </head>
 <body>
 <header>
diff --git a/server/server.go b/server/server.go
index 69ad3e3..4eea512 100644
--- a/server/server.go
+++ b/server/server.go
@@ -1,9 +1,11 @@
 package server
 
 import (
+	"bytes"
 	"fmt"
 	"github.com/1f349/cache"
 	"github.com/1f349/lavender/issuer"
+	"github.com/1f349/lavender/theme"
 	"github.com/1f349/mjwt"
 	"github.com/julienschmidt/httprouter"
 	"github.com/rs/cors"
@@ -68,6 +70,10 @@ func NewHttpServer(conf Conf, signer mjwt.Signer) *HttpServer {
 	r.POST("/popup", hs.flowPopupPost)
 	r.GET("/callback", hs.flowCallback)
 
+	r.GET("/theme/style.css", func(rw http.ResponseWriter, req *http.Request, params httprouter.Params) {
+		http.ServeContent(rw, req, "style.css", time.Now(), bytes.NewReader(theme.DefaultThemeCss))
+	})
+
 	// setup CORS options for `/verify` and `/refresh` endpoints
 	var corsAccessControl = cors.New(cors.Options{
 		AllowOriginFunc: func(origin string) bool {
diff --git a/theme/style.css b/theme/style.css
new file mode 100644
index 0000000..24323c0
--- /dev/null
+++ b/theme/style.css
@@ -0,0 +1,3 @@
+html, body {
+    color-scheme: light dark;
+}
diff --git a/theme/theme.go b/theme/theme.go
new file mode 100644
index 0000000..dd91b87
--- /dev/null
+++ b/theme/theme.go
@@ -0,0 +1,6 @@
+package theme
+
+import _ "embed"
+
+//go:embed style.css
+var DefaultThemeCss []byte
