diff --git a/library/Icinga/Web/Widget/Chart/HistoryColorGrid.php b/library/Icinga/Web/Widget/Chart/HistoryColorGrid.php
index 1a9c20acb..bec7db181 100644
--- a/library/Icinga/Web/Widget/Chart/HistoryColorGrid.php
+++ b/library/Icinga/Web/Widget/Chart/HistoryColorGrid.php
@@ -131,7 +131,7 @@ class HistoryColorGrid extends AbstractWidget {
             '>&nbsp;</a>';
         } else {
             return '<a ' .
-                'style="background-color:' . $this->calculateColor(0) . '; ' . ' opacity: ' . $this->opacity . ';' .
+                'style="background-color:' . $this->calculateColor(0) . '; ' . ' opacity: ' . $this->opacity . ';" ' .
                 'title="No entries for ' . $day . '" ' .
             '></a>';
         }
diff --git a/public/css/icinga/widgets.less b/public/css/icinga/widgets.less
index f546443c4..9fe42c899 100644
--- a/public/css/icinga/widgets.less
+++ b/public/css/icinga/widgets.less
@@ -19,7 +19,7 @@ table.historycolorgrid td {
   margin: 1em;
 }
 
-table.historycolorgrid td.hover {
+table.historycolorgrid td:hover {
   opacity: 0.5;
 }