paper: fix nav-tab jiggle on focus

paper/_bootswatch.scss

@@ -341,9 +341,11 @@ input[type="checkbox"],
 // Navs =======================================================================
 
 .nav-tabs {
-  & > li > a {
-    border: none;
+  > li > a,
+  > li > a:focus {
     margin-right: 0;
+    background-color: transparent;
+    border: none;
     color: $navbar-default-link-color;
     @include box-shadow(inset 0 -1px 0 #ddd);
     @include transition(all 0.2s);
@@ -355,7 +357,8 @@ input[type="checkbox"],
     }
   }
 
-  & > li.active > a {
+  & > li.active > a,
+  & > li.active > a:focus {
     border: none;
     @include box-shadow(inset 0 -2px 0 $brand-primary);
     color: $brand-primary;

paper/bootstrap.css

@@ -7096,9 +7096,11 @@ input[type="checkbox"]:disabled:checked:after,
   -webkit-box-shadow: inset 0 -2px 0 #4caf50;
   box-shadow: inset 0 -2px 0 #4caf50;
 }
-.nav-tabs > li > a {
-  border: none;
+.nav-tabs > li > a,
+.nav-tabs > li > a:focus {
   margin-right: 0;
+  background-color: transparent;
+  border: none;
   color: #666666;
   -webkit-box-shadow: inset 0 -1px 0 #dddddd;
   box-shadow: inset 0 -1px 0 #dddddd;
@@ -7106,19 +7108,22 @@ input[type="checkbox"]:disabled:checked:after,
   -o-transition: all 0.2s;
   transition: all 0.2s;
 }
-.nav-tabs > li > a:hover {
+.nav-tabs > li > a:hover,
+.nav-tabs > li > a:focus:hover {
   background-color: transparent;
   -webkit-box-shadow: inset 0 -2px 0 #2196f3;
   box-shadow: inset 0 -2px 0 #2196f3;
   color: #2196f3;
 }
-.nav-tabs > li.active > a {
+.nav-tabs > li.active > a,
+.nav-tabs > li.active > a:focus {
   border: none;
   -webkit-box-shadow: inset 0 -2px 0 #2196f3;
   box-shadow: inset 0 -2px 0 #2196f3;
   color: #2196f3;
 }
-.nav-tabs > li.active > a:hover {
+.nav-tabs > li.active > a:hover,
+.nav-tabs > li.active > a:focus:hover {
   border: none;
   color: #2196f3;
 }

paper/bootswatch.less

@@ -341,9 +341,11 @@ input[type="checkbox"],
 // Navs =======================================================================
 
 .nav-tabs {
-  & > li > a {
-    border: none;
+  > li > a,
+  > li > a:focus {
     margin-right: 0;
+    background-color: transparent;
+    border: none;
     color: @navbar-default-link-color;
     .box-shadow(inset 0 -1px 0 #ddd);
     .transition(all 0.2s);
@@ -355,7 +357,8 @@ input[type="checkbox"],
     }
   }
 
-  & > li.active > a {
+  & > li.active > a,
+  & > li.active > a:focus {
     border: none;
     .box-shadow(inset 0 -2px 0 @brand-primary);
     color: @brand-primary;