don't use table for label variatons

less/alerts.less

@@ -30,15 +30,14 @@
     font-weight: 500;
     color: darken(@state-warning-text, 10%);
   }
-}
 
-// Adjust close link position
-.close {
-  position: relative;
-  top: -2px;
-  right: -21px;
-  line-height: @line-height-base;
-  color: inherit;
+  // Adjust close link position
+  .close {
+    position: relative;
+    top: -2px;
+    right: -21px;
+    color: inherit;
+  }
 }
 
 // Alternate styles

less/close.less

@@ -11,6 +11,7 @@
   color: #000;
   text-shadow: 0 1px 0 rgba(255,255,255,1);
   .opacity(.2);
+
   &:hover,
   &:focus {
     color: #000;