fix(frontend): remove duplicate select arrow and show the WordPress brand icon

assets/css/main.css

@@ -2676,6 +2676,13 @@ select.form-control {
     position: relative;
 }
 
+/* .form-select::before 已经画了 FA5 箭头，隐藏原生箭头避免出现两个。 */
+.form-select select {
+    -webkit-appearance: none;
+    -moz-appearance: none;
+    appearance: none;
+}
+
 .form-select::before {
     font: normal normal 900 14px/1 "Font Awesome 5 Free";
     content: '\f107';