Fixes LMS-2352 by unifying :hover and :focus styles.

lms/static/sass/elements/_controls.scss

@@ -38,7 +38,7 @@
   box-shadow: 0 1px 0 rgba($white, .3) inset, 0 0 0 rgba($black, 0);
   padding: ($baseline/2) $baseline;
 
-  &:hover, &.active {
+  &:hover, &:active, &:focus {
     text-decoration: none;
   }
 
@@ -54,7 +54,7 @@
   background-color: $action-primary-bg;
   color: $action-primary-fg;
 
-  &:hover, &.active {
+  &:hover, &:active, &:focus {
     background-color: $action-primary-focused-bg;
     color: $action-primary-focused-fg;
   }
@@ -129,7 +129,7 @@
   background: shade($error-color, 25%);
   color: $white;
 
-  &:hover, &:active {
+  &:hover, &:active, &:focus {
     background: $error-color;
     color: $white;
   }

lms/static/sass/elements/_system-feedback.scss

@@ -90,7 +90,7 @@
         text-shadow: none;
         color: inherit;
 
-        &:hover {
+        &:hover, &:focus {
           color: $action-primary-bg;
         }
       }