* {
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}
#div_left_nav {
    display: inline-block;
    vertical-align: top;
}
#left_ul_main {
    width: 180px;
    list-style: none;
    padding: 0px;
    margin: 0px;
}
.left_main_li {
    width: 180px;
    margin-bottom: 5px;
}
.left_main_li:hover .left_sub_a {
    height: 40px;
}
.left_main_li:hover .left_main_li_div {
    background-color: rgb(230, 230, 250);
}
.left_ul_sub {
    list-style: none;
    padding: 0px;
    overflow: hidden;
    transition: height 0.5s ease;
}
.left_main_li_div {
    display: inline-block;
    /*background-color:yellow;*/
    width: 180px;
    height: 40px;
    padding: 10px;
    border-bottom: 1px solid rgb(255, 255, 255)
}
.left_nav_arrow {
    margin-top: 5px;
    display: inline-block;
    float: right;
}
.left_main_a {
    text-decoration: none;
    display: inline-block;
    /*background-color: red;*/
    color: rgb(0, 0, 0);
}
.left_main_a:visited {
    color: rgb(0, 0, 0);
}
.left_main_a:hover {
    color: rgb(0, 191, 255);
}
.left_sub_a {
    text-decoration: none;
    display: block;
    /*background-color: red;*/
    background-color: rgb(230, 230, 250);
    width: 180px;
    height: 0px;
    transition: height 0.5s ease;
    overflow: hidden;
    color: rgb(0, 0, 0);
}
.left_sub_a:visited {
    color: rgb(0, 0, 0);
}
.left_sub_a:hover {
    color: rgb(0, 191, 255);
}
.label_sub_nav {
    display: block;
    margin: 10px;
}