diff --git a/pyproject.toml b/pyproject.toml
index 3268413..dc00527 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -7,6 +7,7 @@ requires-python = ">=3.13"
 dependencies = [
     "pyside6>=6.9.0",
     "pymupdf>=1.24.0",
+    "pyqtdarktheme>=2.1.0",
 ]
 
 [tool.ruff]
diff --git a/src/main.py b/src/main.py
index 3b58b20..1034d72 100644
--- a/src/main.py
+++ b/src/main.py
@@ -4,11 +4,16 @@ from PySide6.QtWidgets import QApplication
 
 from MainWindow import MainWindow
 
+import qdarktheme
+
 
 def main():
     """Haupteinstiegspunkt der Anwendung."""
     # QApplication-Instanz erstellen
     app = QApplication(sys.argv)
+    
+    # Dark Theme aktivieren
+    qdarktheme.setup_theme("auto")
 
     # Hauptfenster erstellen
     window = MainWindow()
diff --git a/uv.lock b/uv.lock
index eeaf0b9..2890e72 100644
--- a/uv.lock
+++ b/uv.lock
@@ -2,6 +2,15 @@ version = 1
 revision = 2
 requires-python = ">=3.13"
 
+[[package]]
+name = "darkdetect"
+version = "0.7.1"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/48/2e/346667de53b48417e6237efd9d076d6530c413666fcbc381adbfeff21ce7/darkdetect-0.7.1.tar.gz", hash = "sha256:47be3cf5134432ddb616bbffc927237718407914993c82809983e7ccebf49013", size = 6976, upload-time = "2022-07-18T21:10:27.64Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/63/bd/b31abc8fcaab163e0b9501020309dd9094b47d609035a23e6ec0a0a8ba10/darkdetect-0.7.1-py2.py3-none-any.whl", hash = "sha256:3efe69f8ecd5f1b7f4fbb0d1d93f656b0e493c45cc49222380ffe2a529cbc866", size = 8199, upload-time = "2022-07-18T21:10:26.178Z" },
+]
+
 [[package]]
 name = "pymupdf"
 version = "1.26.0"
@@ -17,6 +26,18 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/e9/d7/a6ce6629b66921529543c899830104f40dde45d98534d945970ea61ca8c9/pymupdf-1.26.0-cp39-abi3-win_amd64.whl", hash = "sha256:e39cc74ff030d773c4e76b9e5c5919cc4683895b73bd63bfd7a349a53ab5e8d7", size = 18525321, upload-time = "2025-05-22T16:10:01.426Z" },
 ]
 
+[[package]]
+name = "pyqtdarktheme"
+version = "2.1.0"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "darkdetect" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/5c/f1/786feaad7a333072b34a913dbe38aef94b5ae43ad188934f5d70007aea79/pyqtdarktheme-2.1.0.tar.gz", hash = "sha256:5f8274ddfa3a5481ed9743cdb0f9debfeb7ff695b3a0d202a8104361d17dadb8", size = 42186, upload-time = "2022-12-25T08:33:11.662Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/12/cd/8ce0ac84e9f68dc549edcc5cbdeac7511439c5f7ee6c05f1f8826ef05d44/pyqtdarktheme-2.1.0-py3-none-any.whl", hash = "sha256:8739d99502230fbaca42551ea033c9ae31c81c4ebfec2f1ffde38f32a18bea7a", size = 54242, upload-time = "2022-12-25T08:33:10.125Z" },
+]
+
 [[package]]
 name = "pyside6"
 version = "6.9.0"
@@ -83,11 +104,13 @@ version = "0.1.0"
 source = { virtual = "." }
 dependencies = [
     { name = "pymupdf" },
+    { name = "pyqtdarktheme" },
     { name = "pyside6" },
 ]
 
 [package.metadata]
 requires-dist = [
     { name = "pymupdf", specifier = ">=1.24.0" },
+    { name = "pyqtdarktheme", specifier = ">=2.1.0" },
     { name = "pyside6", specifier = ">=6.9.0" },
 ]