.nav{ width:100%; height:55px; margin:0; z-index:999; background:#eee;}.nav .nav_list{width:1230px; margin:auto;height:55px;display:flex;}.nav li{float:left; width:100%;position:relative;flex:1;}.nav li.last{background:none;}.nav li a{float:left;display:block; width:100%;text-align:center; line-height:1.2;}.nav li a:hover{background:#990066;text-decoration:none;color:#fff;}.nav li a span{float:left;display:block; width:100%; height:55px; line-height:55px;cursor:pointer; font-family:"Microsoft YaHei";text-align:center;  font-size:18px;}.nav li a.selected{ background:#990066; color:#fff;}.nav li a.selected2{ background:#990066; color:#fff;}/*===一级当前栏目样式=*//*========以下二级导航样式=*/.nav li.selected .submenu{display:block;}.nav li .submenu{display:none;position:absolute;top:55px;left:0px; background:rgba(0,0,0,0.6);}.nav li .submenu{width:100%;}.nav li .submenu{ z-index:999;}.nav li .submenu li{float:left;padding:0;background:none; font-size:16px;}.nav li .submenu li a{float:none;padding:13px 8px;box-sizing: border-box;text-align: center; font-family:"Microsoft YaHei";background:none; color:#fff; line-height:1.3;}.nav li .submenu li a:hover{background:#990066;font-weight:normal; color:#fff; text-decoration:none;}
.nav_list li {
    position: relative;  /* 必须设置为relative */
}

.submenu {
    display: none;
    position: absolute;
    top: 100%;  /* 确保在菜单项下方显示 */
    left: 0;
    z-index: 999;
    background: #fff;  /* 添加背景色 */
    width: 200px;  /* 设置适当宽度 */
}

.nav_list li:hover .submenu {
    display: block;  /* 鼠标悬停时显示 */
}