chore: use FlightDelayBackgroundDesktop/Mobile.png for background images

Author: christoph2806

src/app/layout.css

@@ -3,13 +3,13 @@ body {
     background-repeat: no-repeat;
     background-size: cover;
     /* background-image: url("/assets/images/FlightDelayBackgroundDesktopLR.png"); */
-    background-image: url("/assets/images/FlightDelayBackgroundDesktopD1ConfLR.png");
+    background-image: url("/assets/images/FlightDelayBackgroundDesktop.png");
 }
 
 @media screen and (max-width:720px) {
     body {
         /* background-image: url("/assets/images/FlightDelayBackgroundMobileLR.png"); */
-        background-image: url("/assets/images/FlightDelayBackgroundMobileD1ConfLR.png");
+        background-image: url("/assets/images/FlightDelayBackgroundMobile.png");
     }
 }