Added style for mark buttons in PG theme.

boards/static/css/pg/base_page.css

@@ -306,3 +306,12 b' input[type="submit"]:hover {'
 .form-email {
     display: none;
 }
+
+.mark_btn {
+    padding: 2px 4px;
+    border: 1px solid;
+}
+
+.mark_btn:hover {
+    background: #ccc;
+}
  No newline at end of file