使用默认样式表中的属性选择器作为重置样式的指南：

select[multiple] {
  background:none;
  width:auto;
  height:auto;
  padding:0;
  margin:0;
  border-width: 2px;
  border-style: inset;
  -moz-appearance: menulist;
  -webkit-appearance: menulist;
  appearance: menulist;
}