offline.css: Add vertical margin to header and footer.

This should make a visible difference only for the top margin of
the footer.

Signed-off-by: Ulrich Müller <[email protected]>

Author: ulm

offline.css

@@ -10,7 +10,7 @@ body {
 
 header, footer {
     padding: 0.75em 1em;
-    margin: 0;
+    margin: 1em 0;
     background-color: #e1e1e1;
 }