docs: remove problematic css

Author: wxsms

docs/.vitepress/theme/theme.less

@@ -45,14 +45,6 @@ body > .alert {
 .uiv {
   @import (less) '../../../node_modules/bootstrap/dist/css/bootstrap.min.css';
 
-  button.btn, a.btn,.btn-group.dropdown {
-    margin: 0 2px;
-  }
-
-  .btn-group .btn {
-    margin: 0;
-  }
-
   table {
     width: auto;