adjust document preview size for bigger screens

src/pfwbged/theme/diazo_resources/static/main.css

@@ -533,6 +533,11 @@ div#fields {
 	width: 700px;
 }
 
+@media screen and (min-width: 1200px) {
+	div#fields { width: calc(98% - 800px); }
+	#fieldset-versions { width: 800px; }
+}
+
 @media screen and (max-width: 800px) {
 	#fieldset-versions {
 		float: none;