enable backgrounds images when printing to pdf (closes #271)

css/print/pdf.css

@@ -10,6 +10,7 @@
    background. This prevents elements from extending
    beyond the edge of the printed page, and prevents
    unnecessary background images from printing */
+
 * {
 	-webkit-print-color-adjust: exact;
 }
@@ -19,16 +20,14 @@ body {
 	width: auto;
 	height: auto;
 	border: 0;
-	margin: 0 5%;
 	padding: 0;
 	float: none !important;
 	overflow: visible;
-	background-image: none !important;
 }
 
 html {
-	width: auto;
+	width: 100%;
-	height: auto;
+	height: 100%;
 	overflow: visible;
 }