paper: tweak button shadows

paper/_bootswatch.scss

@@ -38,14 +38,13 @@
 
 @mixin btn($class,$bg){
   .btn-#{$class} {
-    @include gradient-radial($bg 80%, darken($bg, 6%) 81%);
     background-size: 200%;
     background-position: 50%;
-    transition: background-size 2s;
 
-    &:hover {
-      background-size: 100%;
-      border-color: darken($bg, 6%);
+    &:hover,
+    &:active:hover,
+    &:focus {
+      background-color: darken($bg, 6%);
     }
 
     &:active {

paper/bootstrap.css

@@ -6610,21 +6610,14 @@ button.close {
   margin-top: 2px;
 }
 .btn-default {
-  background-image: -webkit-radial-gradient(circle, #ffffff 80%, #f0f0f0 81%);
-  background-image: -o-radial-gradient(circle, #ffffff 80%, #f0f0f0 81%);
-  background-image: radial-gradient(circle, #ffffff 80%, #f0f0f0 81%);
-  background-repeat: no-repeat;
   -webkit-background-size: 200% 200%;
           background-size: 200%;
   background-position: 50%;
-  -webkit-transition: background-size 2s;
-       -o-transition: background-size 2s;
-          transition: background-size 2s;
 }
-.btn-default:hover {
-  -webkit-background-size: 100% 100%;
-          background-size: 100%;
-  border-color: #f0f0f0;
+.btn-default:hover,
+.btn-default:active:hover,
+.btn-default:focus {
+  background-color: #f0f0f0;
 }
 .btn-default:active {
   background-color: #f0f0f0;
@@ -6638,21 +6631,14 @@ button.close {
   box-shadow: 2px 2px 2px rgba(0, 0, 0, 0.3);
 }
 .btn-primary {
-  background-image: -webkit-radial-gradient(circle, #2196f3 80%, #0d87e9 81%);
-  background-image: -o-radial-gradient(circle, #2196f3 80%, #0d87e9 81%);
-  background-image: radial-gradient(circle, #2196f3 80%, #0d87e9 81%);
-  background-repeat: no-repeat;
   -webkit-background-size: 200% 200%;
           background-size: 200%;
   background-position: 50%;
-  -webkit-transition: background-size 2s;
-       -o-transition: background-size 2s;
-          transition: background-size 2s;
 }
-.btn-primary:hover {
-  -webkit-background-size: 100% 100%;
-          background-size: 100%;
-  border-color: #0d87e9;
+.btn-primary:hover,
+.btn-primary:active:hover,
+.btn-primary:focus {
+  background-color: #0d87e9;
 }
 .btn-primary:active {
   background-color: #0d87e9;
@@ -6666,21 +6652,14 @@ button.close {
   box-shadow: 2px 2px 2px rgba(0, 0, 0, 0.3);
 }
 .btn-success {
-  background-image: -webkit-radial-gradient(circle, #4caf50 80%, #439a46 81%);
-  background-image: -o-radial-gradient(circle, #4caf50 80%, #439a46 81%);
-  background-image: radial-gradient(circle, #4caf50 80%, #439a46 81%);
-  background-repeat: no-repeat;
   -webkit-background-size: 200% 200%;
           background-size: 200%;
   background-position: 50%;
-  -webkit-transition: background-size 2s;
-       -o-transition: background-size 2s;
-          transition: background-size 2s;
 }
-.btn-success:hover {
-  -webkit-background-size: 100% 100%;
-          background-size: 100%;
-  border-color: #439a46;
+.btn-success:hover,
+.btn-success:active:hover,
+.btn-success:focus {
+  background-color: #439a46;
 }
 .btn-success:active {
   background-color: #439a46;
@@ -6694,21 +6673,14 @@ button.close {
   box-shadow: 2px 2px 2px rgba(0, 0, 0, 0.3);
 }
 .btn-info {
-  background-image: -webkit-radial-gradient(circle, #9c27b0 80%, #862197 81%);
-  background-image: -o-radial-gradient(circle, #9c27b0 80%, #862197 81%);
-  background-image: radial-gradient(circle, #9c27b0 80%, #862197 81%);
-  background-repeat: no-repeat;
   -webkit-background-size: 200% 200%;
           background-size: 200%;
   background-position: 50%;
-  -webkit-transition: background-size 2s;
-       -o-transition: background-size 2s;
-          transition: background-size 2s;
 }
-.btn-info:hover {
-  -webkit-background-size: 100% 100%;
-          background-size: 100%;
-  border-color: #862197;
+.btn-info:hover,
+.btn-info:active:hover,
+.btn-info:focus {
+  background-color: #862197;
 }
 .btn-info:active {
   background-color: #862197;
@@ -6722,21 +6694,14 @@ button.close {
   box-shadow: 2px 2px 2px rgba(0, 0, 0, 0.3);
 }
 .btn-warning {
-  background-image: -webkit-radial-gradient(circle, #ff9800 80%, #e08600 81%);
-  background-image: -o-radial-gradient(circle, #ff9800 80%, #e08600 81%);
-  background-image: radial-gradient(circle, #ff9800 80%, #e08600 81%);
-  background-repeat: no-repeat;
   -webkit-background-size: 200% 200%;
           background-size: 200%;
   background-position: 50%;
-  -webkit-transition: background-size 2s;
-       -o-transition: background-size 2s;
-          transition: background-size 2s;
 }
-.btn-warning:hover {
-  -webkit-background-size: 100% 100%;
-          background-size: 100%;
-  border-color: #e08600;
+.btn-warning:hover,
+.btn-warning:active:hover,
+.btn-warning:focus {
+  background-color: #e08600;
 }
 .btn-warning:active {
   background-color: #e08600;
@@ -6750,21 +6715,14 @@ button.close {
   box-shadow: 2px 2px 2px rgba(0, 0, 0, 0.3);
 }
 .btn-danger {
-  background-image: -webkit-radial-gradient(circle, #e51c23 80%, #cb171e 81%);
-  background-image: -o-radial-gradient(circle, #e51c23 80%, #cb171e 81%);
-  background-image: radial-gradient(circle, #e51c23 80%, #cb171e 81%);
-  background-repeat: no-repeat;
   -webkit-background-size: 200% 200%;
           background-size: 200%;
   background-position: 50%;
-  -webkit-transition: background-size 2s;
-       -o-transition: background-size 2s;
-          transition: background-size 2s;
-}
-.btn-danger:hover {
-  -webkit-background-size: 100% 100%;
-          background-size: 100%;
-  border-color: #cb171e;
+}
+.btn-danger:hover,
+.btn-danger:active:hover,
+.btn-danger:focus {
+  background-color: #cb171e;
 }
 .btn-danger:active {
   background-color: #cb171e;

paper/bootswatch.less

@@ -38,14 +38,13 @@
 
 #btn(@class,@bg) {
   .btn-@{class} {
-    #gradient > .radial(@bg 80%, darken(@bg, 6%) 81%);
     background-size: 200%;
     background-position: 50%;
-    transition: background-size 2s;
 
-    &:hover {
-      background-size: 100%;
-      border-color: darken(@bg, 6%);
+    &:hover,
+    &:active:hover,
+    &:focus {
+      background-color: darken(@bg, 6%);
     }
 
     &:active {