/* 头部 */
/* 默认导航栏样式 */
.nav_tab_box {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    background: transparent;
    /* 初始透明 */
    transition: all 0.4s ease;
    /* 平滑过渡 */
}

/* 滚动后的导航栏样式 */
.nav_tab_box.scrolled {
    background: linear-gradient(to bottom, #f5f5f5, #e0e0e0);
    /* 灰色渐变色 */
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    /* 可选：添加阴影增强效果 */
}

.nav_pc {
    display: flex;
    justify-content: space-between;
}

.nav_mb {
    display: none;
}

.menu_bar {
    display: flex;
}

.logo_pc img {
    margin-top: 25px;
    margin-bottom: 25px;
}

.menu_bar .menu_bar_link {
    font-size: 18px;
    font-weight: 500;
    color: #fff;
    display: flex;
    align-items: center;
    height: 100%;
    padding: 0 20px;
}

@media screen and (max-width: 1750px) {
    .logo_pc img {
        margin-top: 20px;
        margin-bottom: 20px;
        width: 185px;
    }

}

@media screen and (max-width: 750px) {
    .nav_mb {
        display: block;
    }

    .nav_pc {
        display: none;
    }
}