Fix pmahomme's outline buttons CSS

Signed-off-by: Maurício Meneghini Fauth <mauricio@fauth.dev>

themes/pmahomme/scss/_buttons.scss

@@ -1,4 +1,5 @@
-.btn-primary {
+.btn-primary,
+.btn-outline-primary {
   font-weight: $font-weight-bold;
 }
 
@@ -12,3 +13,9 @@
     background-image: linear-gradient(#fff, #ddd);
   }
 }
+
+.btn-outline-primary,
+.btn-outline-secondary {
+  color: $body-color;
+  border-color: #aaa;
+}