--- a/browser/extensions/activity-stream/css/activity-stream-linux.css
+++ b/browser/extensions/activity-stream/css/activity-stream-linux.css
@@ -1024,17 +1024,19 @@ section.top-sites:not(.collapsed):hover 
       max-height: 230px; }
     .card-outer .card-text:not(.no-description) .card-title {
       max-height: 57px;
       overflow: hidden; }
   .card-outer .card-host-name {
     color: #737373;
     font-size: 10px;
     padding-bottom: 4px;
-    text-transform: uppercase; }
+    text-transform: uppercase;
+    overflow: hidden;
+    text-overflow: ellipsis; }
   .card-outer .card-title {
     margin: 0 0 2px;
     font-size: 14px;
     word-wrap: break-word;
     line-height: 19px; }
   .card-outer .card-description {
     font-size: 12px;
     margin: 0;

--- a/browser/extensions/activity-stream/css/activity-stream-mac.css
+++ b/browser/extensions/activity-stream/css/activity-stream-mac.css
@@ -1024,17 +1024,19 @@ section.top-sites:not(.collapsed):hover 
       max-height: 230px; }
     .card-outer .card-text:not(.no-description) .card-title {
       max-height: 57px;
       overflow: hidden; }
   .card-outer .card-host-name {
     color: #737373;
     font-size: 10px;
     padding-bottom: 4px;
-    text-transform: uppercase; }
+    text-transform: uppercase;
+    overflow: hidden;
+    text-overflow: ellipsis; }
   .card-outer .card-title {
     margin: 0 0 2px;
     font-size: 14px;
     word-wrap: break-word;
     line-height: 19px; }
   .card-outer .card-description {
     font-size: 12px;
     margin: 0;

--- a/browser/extensions/activity-stream/css/activity-stream-windows.css
+++ b/browser/extensions/activity-stream/css/activity-stream-windows.css
@@ -1024,17 +1024,19 @@ section.top-sites:not(.collapsed):hover 
       max-height: 230px; }
     .card-outer .card-text:not(.no-description) .card-title {
       max-height: 57px;
       overflow: hidden; }
   .card-outer .card-host-name {
     color: #737373;
     font-size: 10px;
     padding-bottom: 4px;
-    text-transform: uppercase; }
+    text-transform: uppercase;
+    overflow: hidden;
+    text-overflow: ellipsis; }
   .card-outer .card-title {
     margin: 0 0 2px;
     font-size: 14px;
     word-wrap: break-word;
     line-height: 19px; }
   .card-outer .card-description {
     font-size: 12px;
     margin: 0;