diff --git a/core/themes/seven/style.css b/core/themes/seven/style.css
index e5869d3..6665e41 100644
--- a/core/themes/seven/style.css
+++ b/core/themes/seven/style.css
@@ -490,6 +490,13 @@ table th.active img {
   top: 3px;
   right: 3px; /* LTR */
 }
+/*
+ * Checkbox have different width size in cross-browsers. Set width to a minimum
+ * value that trigger browsers to automatically size minimum width of TH element.
+ */
+table th.select-all {
+  width: 1px;
+}
 table td.active {
   background: #e9e9dd;
 }