* remove text-shadow from buttons.

src/less/controls/buttons.less

 /// ========================================================================
 /// Bootstrap: buttons.less
 /// https://github.com/twbs/bootstrap/blob/master/less/buttons.less
-/// 
+///
 /// ZUI: The file has been changed in ZUI. It will not keep update with the
 /// Bootsrap version in the future.
 /// http://zui.sexy
@@ -59,32 +59,26 @@
 // Default button
 .btn {
   .button-variant(@btn-default-color; @btn-default-bg; @btn-default-border);
-  text-shadow: 0 1px 0 #fff;
 }
 // Primary button
 .btn-primary {
   .button-variant(@btn-primary-color; @btn-primary-bg; @btn-primary-border);
-  text-shadow: 0 -1px 0 rgba(0,0,0,.2);
 }
 // Warning appears as orange
 .btn-warning {
   .button-variant(@btn-warning-color; @btn-warning-bg; @btn-warning-border);
-  text-shadow: 0 -1px 0 rgba(0,0,0,.2);
 }
 // Danger and error appear as red
 .btn-danger {
   .button-variant(@btn-danger-color; @btn-danger-bg; @btn-danger-border);
-  text-shadow: 0 -1px 0 rgba(0,0,0,.2);
 }
 // Success appears as green
 .btn-success {
   .button-variant(@btn-success-color; @btn-success-bg; @btn-success-border);
-  text-shadow: 0 -1px 0 rgba(0,0,0,.2);
 }
 // Info appears as blue-green
 .btn-info {
   .button-variant(@btn-info-color; @btn-info-bg; @btn-info-border);
-  text-shadow: 0 -1px 0 rgba(0,0,0,.2);
 }