CSS styles for null checkbox and for NULL values in table cells.

themes/original/css/theme_right.css.php

@@ -159,6 +159,12 @@ fieldset.tblFooters {
     clear:              both;
 }
 
+div.null_div {
+    height: 20px;
+    text-align: center;
+    font-style:normal;
+}
+
 fieldset .formelement {
     float:              <?php echo $left; ?>;
     margin-<?php echo $right; ?>:       0.5em;
@@ -235,6 +241,14 @@ th.condition {
     border: 1px solid <?php echo $GLOBALS['cfg']['BrowseMarkerBackground']; ?>;
 }
 
+/**
+ * cells with the value NULL
+ */
+td.null {
+    font-style: italic;
+    text-align: <?php echo $right; ?>;
+}
+
 table .value {
     text-align:         <?php echo $right; ?>;
     white-space:        normal;