diff --git a/mailgo.d.ts b/mailgo.d.ts
index 15dd267..8530d5c 100644
--- a/mailgo.d.ts
+++ b/mailgo.d.ts
@@ -9,7 +9,6 @@ export type MailgoConfig = {
   lang?: string;
   forceLang?: boolean;
   dark?: boolean;
-  // additionalCSS?: string;
   // TODO here mailgo configurations!
 };
 
diff --git a/src/mailgo.scss b/src/mailgo.scss
index 012969d..650755d 100644
--- a/src/mailgo.scss
+++ b/src/mailgo.scss
@@ -166,6 +166,6 @@ $default-border-radius: 20px;
     }
   }
 
-  &.dark {
+  &.m-dark {
   }
 }
diff --git a/src/mailgo.ts b/src/mailgo.ts
index ab00775..9ca3413 100644
--- a/src/mailgo.ts
+++ b/src/mailgo.ts
@@ -101,6 +101,11 @@ const mailgoInit = (mailgoConfig?: MailgoConfig): void => {
     modal.id = "mailgo";
     modal.classList.add("m-modal");
 
+    // if dark is in config
+    if (mailgoConfig?.dark) {
+      modal.classList.add("m-dark");
+    }
+
     // background
     let modalBackground = createElement();
     modalBackground.className = "m-modal-back";