Fixed file browser glitches

src/filebrowser/theme.css

@@ -34,7 +34,6 @@
 .jp-FileButtons {
   border-top: 1px solid #E0E0E0;
   border-bottom: 1px solid #E0E0E0;
-  padding: 9px 0;
 }
 
 
@@ -47,6 +46,8 @@
   border: none;
   font-size: 16px;
   outline: 0;
+  padding-top: 12px;
+  padding-bottom: 12px;
 }