--- a/toolkit/themes/linux/global/in-content/common.css
+++ b/toolkit/themes/linux/global/in-content/common.css
@@ -7,16 +7,17 @@
 xul|tab[visuallyselected] {
   /* Override styles for tab[selected] from
      toolkit/themes/linux/global/tabbox.css */
   margin-bottom: 0;
   border-bottom-left-radius: 0;
   border-bottom-right-radius: 0;
 }
 
+*|button.primary:focus,
 xul|button:-moz-focusring {
   outline: 1px dotted;
   outline-offset: -2px;
 }
 
 xul|button > xul|*.button-box,
 xul|menulist > xul|*.menulist-label-box {
   -moz-appearance: none;

--- a/toolkit/themes/osx/global/in-content/common.css
+++ b/toolkit/themes/osx/global/in-content/common.css
@@ -61,16 +61,17 @@ xul|*.text-link:-moz-focusring {
   color: var(--in-content-link-highlight);
   text-decoration: underline;
   box-shadow: none;
 }
 
 xul|button:-moz-focusring,
 xul|menulist:-moz-focusring,
 xul|checkbox:-moz-focusring > .checkbox-check,
+*|button.primary:focus,
 html|input[type="checkbox"]:-moz-focusring + html|label:before,
 xul|radio[focused="true"] > .radio-check,
 xul|tab:-moz-focusring > .tab-middle > .tab-text {
   outline: 2px solid rgba(0,149,221,0.5);
   outline-offset: 1px;
   -moz-outline-radius: 2px;
 }
 

--- a/toolkit/themes/windows/global/in-content/common.css
+++ b/toolkit/themes/windows/global/in-content/common.css
@@ -41,16 +41,21 @@ xul|*.menulist-label-box {
   border-style: none;
 }
 
 xul|menulist:-moz-focusring > xul|*.menulist-label-box,
 html|input[type="checkbox"]:-moz-focusring + html|label:before {
   outline: 1px dotted;
 }
 
+*|button.primary:focus {
+  outline: 1px dotted;
+  outline-offset: -3px;
+}
+
 /* Use a 2px border so that selected row highlight is still visible behind
     an existing high-contrast border that uses the background color */
 @media (-moz-windows-default-theme: 0) {
   xul|treechildren::-moz-tree-row(selected),
   xul|listbox xul|listitem[selected="true"] {
      border: 2px dotted Highlight;
   }
 }