.nav dl.chang {
    width: 200%;}

.nav dl.chang dd {
    position: relative;}
    .mainmenu dl {
        display: none;
        position: absolute;}
    
    .third-level {
        display: none;
        position: absolute;
        left: 100%;
        top: 0;
        background-color:#b30216;
        /* 其他样式... */
        width: 105%;
        font-size: 14px;}
    
    .third-level li {
        width: 100%;
        height: 100%;}
    .third-level a {
        font-size: 14px;}
    
    .mainmenu:hover > dl {
        display: block;}
    
    .mainmenu dl dd:hover .third-level {
        display: block;}
.has-submenu {
    position: relative;}

.submenu-content {
    position: absolute;
    top: 100%;
    left: 0;
    background: #fff;
    border: 1px solid #ddd;
    border-radius: 4px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    min-width: 180px;
    z-index: 100;
    padding: 5px 0;
    margin-top: 5px;}

.submenu-content li {
    padding-left: 15px;}

.submenu-content li:hover {
    background-color: #f5f5f5;}

.submenu-content a {
    display: block;
    color: #333;
    text-decoration: none;
    white-space: nowrap;}

.submenu-indicator {
    margin-left: 5px;
    font-size: 0.8em;}