change bg-image position

src/client/styles/scss/theme/spring.scss

@@ -19,7 +19,7 @@
   .page-editor-preview-container {
     background-image: url('/images/themes/spring/spring02.svg');
     background-attachment: fixed;
-    background-position: center center;
+    background-position: bottom;
     background-size: cover;
   }
 }
@@ -28,7 +28,7 @@
   #page-wrapper {
     background-image: url('/images/themes/spring/spring.svg');
     background-attachment: fixed;
-    background-position: center center;
+    background-position: bottom;
     background-size: cover;
   }
 }