ul {
    /* 取消ul預設的內縮及樣式 */
    margin: 0;
    padding: 0;
    list-style: none;
    position: absolute;
    top: 15px;
    left: 350px;
    z-index: 2000;
    float: none;
}

@media screen and (max-width:768px) {
    ul {
        left: 140px;
    }
}

ul.drop-down-menu {
    display: inline-block;
    text-align: center;
}

ul.drop-down-menu li {
    position: relative;
    /* white-space: nowrap; */
    white-space: wrap;
    float: none;
    border-bottom: solid #CCC 1px;
}

ul.drop-down-menu>li:last-child {
    border-right: none;
}


/*ul.drop-down-menu>li {
	float: right;
	/* 只有第一層是靠左對齊*
  }*/

ul.drop-down-menu a {
    /*background-color: rgba(0, 0, 0, .5);*/
    color: #fff;
    display: block;
    padding: 0 20px;
    text-decoration: none;
    line-height: 24px;
    font-size: 1rem;
    border: #fff 1px solid;
}

ul.drop-down-menu a:hover {
    /* 滑鼠滑入按鈕變色*/
    background-color: #fff;
    color: #000;
    cursor: pointer;
    width: auto;
}

ul.drop-down-menu li:hover>a {
    /* 滑鼠移入次選單上層按鈕保持變色*/
    background-color: #fff;
    color: #000;
}

ul.drop-down-menu ul {
    border: #fff 1px solid;
    position: absolute;
    z-index: 99;
    left: -23%;
    top: 100%;
    background-color: #fff;
    /*min-width: 180px;*/
}

ul.drop-down-menu ul li a {
    /*border-bottom: #ccc 1px solid;*/
    color: #000;
    line-height: 2rem;
}

ul.drop-down-menu ul li a:hover {
    color: #fff;
    background: #000;
}

ul.drop-down-menu ul li:last-child {
    border-bottom: none;
}

ul.drop-down-menu ul {
    /*隱藏次選單*/
    display: none;
}

ul.drop-down-menu li:hover>ul {
    /* 滑鼠滑入展開次選單*/
    display: block;
}