.header{
    width: 100%;
    height: 12vh;
    display: flex;
    align-items: center;
    justify-content: space-between;
    /* background: #fff; */
    background-color: rgba(255, 255, 255, 0.1);
    z-index: 1000;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    transition: background 0.3s;
}


  .header.scrolled {
    background-color: #fff;
    box-shadow: 0 2px 16px rgba(0,0,0,0.04); /* 可选：加阴影提升层次 */
  }

.logo{
    width: 20%;
    height: 100%;
    /* background: palegoldenrod; */
    display: flex;
    align-items: center;
    padding-left: 8vw;
}
.logo img{
    width: 8vw;
    height: auto;
}

.nav{
    width: 46%;
    height: 100%;
   display: flex;
   align-items: center;
   justify-content: center;
   padding-right: 8vw;
   /* background: palegoldenrod; */
}

.nav-list{
    width: 100%;
    height: 43%;        
    display: flex;
    align-items: center;
    justify-content: space-around;
    /* background: paleturquoise; */
}

.nav-item{
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
   
}

.nav-item a{
    color: #1A2B3C;
    font-size: 0.9vw;
    position: relative;
    text-decoration: none;
    display: inline-block; 
}

.nav-item a.active {
   
    color: #3478FD;

   
}
/* .nav-item a.active::before {
    content: '';
    width: 100%;
    height: 1px;
    background: #00a0d1;
    position: absolute;
    bottom: -5px; 
    left: 0;
    display: block; 
} */

.nav-item a:hover{
    color: #3478FD;
}

/* 下拉菜单 */
.nav-dropdown {
    position: relative;
}
.arrow {
    margin-left: 4px;
    font-size: 0.8em;
}


.dropdown-menu li {
    padding: 0;
    list-style: none;
    
}
.dropdown-menu li a {
    display: flex;
    align-items: center;
    padding: 10px 24px;
    color: #1A2B3C;
    font-size: 1em;
    white-space: nowrap;
    transition: background 0.2s;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.dropdown-menu li a:hover {
    background: #f2f8fa;
    color: #3478FD;
}
.dropdown-mask {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0; top: 0; right: 0; bottom: 0;
    background: rgba(0,0,0,0.08);
}
/*  下拉激活时显示 */
.nav-dropdown.open .dropdown-menu {
    display: block;
}

.dropdown-mask.active {
    display: block;
}

.arrow {
    display: inline-block;
    margin-left: 6px;
    width: 0;
    height: 0;
    vertical-align: middle;
    border-left: 5px solid transparent;
    border-right: 5px solid transparent;
    border-top: 5px solid #1A2B3C;
    transition: transform 0.2s;
}
.nav-dropdown.open .arrow {
    transform: rotate(180deg);
  
    border-top: 5px solid #3478FD;
}
.nav-dropdown a:hover .arrow{
    border-top: 5px solid #3478FD;
}

/* 下拉菜单动画 */
.dropdown-menu {
    display: block; /* 让动画生效，实际用visibility控制显示 */
    /* opacity: 0; */
    transform: translateY(10px);
    visibility: hidden;
    pointer-events: none;
    transition: opacity 0.25s cubic-bezier(.4,0,.2,1), 
                transform 0.25s cubic-bezier(.4,0,.2,1), 
                visibility 0.25s;
    position: absolute;
    top: 8vh;
    left: 0;
    min-width:15vw;
    background: #fff;
    box-shadow: 0 4px 24px rgba(0,0,0,0.12);
    border-radius: 8px;
    z-index: 1001;
    padding: 12px 0;
}
.nav-dropdown.open .dropdown-menu {
    opacity: 1;
    transform: translateY(0);
    visibility: visible;
    pointer-events: auto;
}


.dropdown-item{
    display: inline-block;
    margin-left: 6px;
    width: 0;
    height: 0;
    vertical-align: middle;
    border-top: 5px solid transparent;
    border-bottom: 5px solid transparent;
    border-left: 5px solid #1A2B3C;
    transition: transform 0.2s;
    transition: all 0.2s;
}
.dropdown-item img{
    width: 50%;
    height: auto;
}
/* hover 时去掉背景色，加边框 */
.dropdown-menu li:hover .dropdown-item {
   transform: scale(1.1);
   border-left: 5px solid #3478FD;
}

.dropdown-menu li:hover .dropdown-item img {
    filter: brightness(0) saturate(100%) invert(41%) sepia(99%) saturate(749%) hue-rotate(162deg) brightness(97%) contrast(101%);
    transition: all 0.3s ease;
}
/* 联系我们 */
.contactUs{

    border-radius: 30px;
    transition:  box-shadow 0.2s,  background 0.3s,transform 0.2s;
    background: #3478FD;
    margin-left: 6vw;
}

.contactUs:focus,
.contactUs:hover {
    box-shadow: 0 8px 24px rgba(26, 109, 197, 0.22);
    /* background: linear-gradient(100deg, #4fd7fa 0%, #2a7be0 100%); */
    transform: translateY(-2px) scale(1.03);
}

.contactUs .contactUs-email {
    transition: 
        box-shadow 0.2s,
        background 0.2s,
        transform 0.2s;
}

.contactUs:focus .contactUs-email,
.contactUs:hover .contactUs-email {
    /* background: #e6f7ff; */
    /* box-shadow: 0 0 0 4px rgba(54,198,240,0.15); */
    transform: scale(1.12) rotate(-6deg);
}


.contactUs a{
    width: 100%;
    height: 100%;
    color: #fff;
    display: inline-block;
    display: flex;
    align-items: center;
    justify-content: center;
    /* background: palevioletred; */
   
}

.contactUs a span {
    transition: color 0.2s, font-weight 0.2s;
    font-size: 0.8vw;
}

.contactUs:focus a span,
.contactUs:hover a span {
    color: #fff;
    font-weight: 600;
}

.contactUs-email{
    display: flex;
    align-items: center;
    justify-content: center;    
    width: 1.6vw;
    height: 1.6vw;
    border-radius: 50%;
    /* background: #fff; */
    margin-left: 0.5vw;
}

.contactUs-email img{
    width: 60%;
    height: auto;
}


.menu-active .dropdown-item {
    background: transparent;
    border: 1px solid #00a0d1  
    

}

.menu-active .dropdown-item img {
    filter: brightness(0) saturate(100%) invert(41%) sepia(99%) saturate(749%) hue-rotate(162deg) brightness(97%) contrast(101%);
    transition: all 0.3s ease;
}

.dropdown-menu li a.menu-active {
    background: #f2f8fa;
    color: #007a9e;
}