update font-sizes to be whole-number px values when converted

Author: tilomitra

src/forms/css/forms-r.css

@@ -57,7 +57,7 @@
     .pure-form-message-inline,
     .pure-form-message {
         display: block;
-        font-size: 80%;
+        font-size: 0.75em;
         /* Increased bottom padding to make it group with its related input element. */
         padding: 0.2em 0 0.8em;
     }

src/forms/css/forms.css

@@ -285,12 +285,12 @@ since IE8 won't execute CSS that contains a CSS3 selector.
     padding-left: 0.3em;
     color: #666;
     vertical-align: middle;
-    font-size: 90%;
+    font-size: 0.875em;
 }
 
 /* Block help for forms */
 .pure-form-message {
     display: block;
     color: #666;
-    font-size: 90%;
+    font-size: 0.875em;
 }