make tables display slightly better in the dungeon theme

this might be worth moving into the non-basic themes

custom-static/css/dungeon.css

@@ -15,6 +15,10 @@ h1, h2, h3, h4, h5, h6 {
     line-height: 1.2em;
 }
 
+table {
+    width: 100%;
+}
+
 .dungeon h2 ~ p {
     margin: 0.5em 0;
 }