Update screen.css

adding <sub> styles that are missing

assets/css/screen.css

@@ -495,6 +495,10 @@ article .text sup {
     vertical-align: super;
     font-size: smaller
 }
+article .text sub {
+    vertical-align: sub;
+    font-size: small
+}
 article .text small {
     font-size: 13px;
     color: #909396
@@ -1635,4 +1639,4 @@ body.touch.user article .readmore {
     body.noimage article {
         margin-top: 24px
     }
-}
+}