优化多选下拉列表初始化样式

public/assets/css/backend.css

@@ -153,6 +153,10 @@ select.selectpicker {
   max-height: 31px;
   overflow: hidden;
 }
+select.bs-select-hidden[multiple] > option,
+select.selectpicker[multiple] > option {
+  height: 31px;
+}
 .img-center {
   margin: 0 auto;
   display: inline;

public/assets/less/backend.less

@@ -197,6 +197,9 @@ select.bs-select-hidden, select.selectpicker {
   display: inherit !important;
   max-height: 31px;
   overflow: hidden;
+  &[multiple] > option {
+    height:31px;
+  }
 }
 
 .img-center {