Fix Chrome page break problem

Fixes the first part of #40

generator/css/output.css

 }
 
 body {
-    display: flex;
-    justify-content:center;
-    align-content:center;
+  margin: 0;
+  padding: 0;
 }
 
 .page-preview {
     margin: 0;
     padding: 0;
     border: 0;
-    box-shadow: 0;
+    box-shadow: none;
     background-color: white;
   }
   .page-background {
     margin: 0;
     padding: 0;
     border: 0;
-    box-shadow: 0;
+    box-shadow: none;
     /* Set the background to gray to visualize the page size in the print preview */
     background-color: gray;
   }
-}
+}