.head {
    height: 170px;
}

.head .log_research {
    display: flex;
    flex-direction: column;
    align-items: center;
    flex-direction: row;
    justify-content: space-between;
    margin: 0 auto;
    height: 120px;
    width: 1445px;
}

.head_log {
    width: 340px;
    height: 90px;
    background: url("../img/logo.png") no-repeat center;
}

.research_box {
    display: flex;
    align-items: center;
    width: 260px;
    height: 30px;
    border: 2px solid #b5b5b5;
    border-radius: 10px;
}

.research_input {
    width: 178px;   
    height: 30px;
    border: none;
}

.research_icon {
    margin-left: 10px;
    width: 25px;
    height: 30px;
    background: url("../img/search.png") no-repeat center;
    background-size: contain;
}

.line {
    width: 2px;
    height: 20px;
    border-left: 2px solid #b5b5b5;
}

.research_button {
    width: 60px;
    height: 100%;
    font-size: 15px;
    line-height: 30px;
    text-align: center;
    color: #b5b5b5;
}

.nav {
    height: 44px;
    border-bottom: 6px solid #b5b5b5;
}

.nav_box {
    margin: 0 auto;
    width: 1200px;
    height: 100%;
}

.level_1_nav {
    display: flex;
    justify-content: space-between;
    height: 100%;
}

.level_1_nav li {
    display: inline-block;
    height: 100%;
    font-size: 17px;
    width: 102px;
}

.level_1_nav li a {
    display: inline-block;
    line-height: 44px;
    width: 100%;
    height: 100%;
    font-weight: 600;
}

.level_1_nav>li:hover {
    color: #0079c0;
}

.level_1_nav>li:hover .level_2_nav {
    display: flex;
    flex-direction: column;
    position: absolute;
    width: 114px;
    height: 40px;
    white-space: nowrap;
    color: #0079c0;


}

.level_2_nav {
    display: none;
    position: relative;
    z-index: 11;
}

.level_2_nav>li {
    display: inline-block;
    width: 102px;
    height: 45px;
    color: #0079c0;
    background-color: rgba(255, 255, 255, 0.523);
}

.level_2_nav>li>a {
    margin-bottom: 4px;
    width: 80%;
    height: 31px;
    /* letter-spacing: .4em; */
    line-height: 31px;
    font-weight: 500;
    border-bottom: 2px solid white;
    font-size: 16px;
}

.level_2_nav>li>a:hover {
    color: black;
}