Small ui fix

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/sections/merge_requests.scss

@@ -21,11 +21,11 @@
 
 .merge-request .merge-request-tabs{
   border-bottom: 2px solid $border_primary;
-  margin-bottom: 20px;
+  margin: 20px 0;
 
   li {
     a {
-      padding: 18px 40px;
+      padding: 15px 40px;
       font-size: 14px;
       margin-bottom: -2px;
       border-bottom: 2px solid $border_primary;