diff --git a/main/ui/src/main/java/org/cryptomator/ui/FxApplicationComponent.java b/main/ui/src/main/java/org/cryptomator/ui/FxApplicationComponent.java
index ac000565c..165b143ea 100644
--- a/main/ui/src/main/java/org/cryptomator/ui/FxApplicationComponent.java
+++ b/main/ui/src/main/java/org/cryptomator/ui/FxApplicationComponent.java
@@ -18,6 +18,7 @@ public interface FxApplicationComponent {
 	default void start() {
 		Platform.startup(() -> {
 			assert Platform.isFxApplicationThread();
+			Application.setUserAgentStylesheet(getClass().getResource("/css/theme.css").toString());
 			application().start();
 		});
 	}
diff --git a/main/ui/src/main/resources/css/theme.css b/main/ui/src/main/resources/css/theme.css
new file mode 100644
index 000000000..1743598b8
--- /dev/null
+++ b/main/ui/src/main/resources/css/theme.css
@@ -0,0 +1,34 @@
+/*******************************************************************************
+ *                                                                             *
+ * COLORS                                                                      *
+ *                                                                             *
+ ******************************************************************************/
+ 
+.root {
+	WHITE: #FFF;
+	PRIMARY_BG: #79B01A;
+}
+
+
+/*******************************************************************************
+ *                                                                             *
+ * Main Window                                                                 *
+ *                                                                             *
+ ******************************************************************************/
+ 
+.main-window .title {
+	-fx-background-color: PRIMARY_BG;
+}
+
+
+/*******************************************************************************
+ *                                                                             *
+ * Tooltip                                                                     *
+ *                                                                             *
+ ******************************************************************************/
+
+.tooltip {
+	-fx-background-color: WHITE;
+    -fx-padding: 0.2em 0.4em 0.2em 0.4em;
+    -fx-font-size: 0.8em;
+}
\ No newline at end of file