chore: rm obsolete style

Author: picodoth

assets/index.less

@@ -110,7 +110,6 @@
   &-horizontal {
     background-color: #F3F5F7;
     border: none;
-    border-bottom: 1px solid transparent;
     border-bottom: 1px solid #d9d9d9;
     box-shadow: none;