#header {
    background-color: #fff;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
}

#header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 80px;
    padding: 10px 15px;
}

.logo {
    display: flex;
    align-items: center;
}

.logo a {
    display: flex;
    align-items: center;
}

.logo img {
    height: 48px; /* 缩小到80%: 60px * 0.8 = 48px */
    margin-right: 10px;
    object-fit: contain;
}

.logo span {
    font-size: 20px;
    font-weight: 700;
    color: var(--primary-color);
}

.logo .en {
    font-size: 14px;
    font-weight: 400;
    margin-left: 10px;
    color: var(--secondary-color);
}

#header nav {
    display: flex;
    align-items: center;
}

#header nav ul {
    display: flex;
}

#header nav li {
    margin: 0 15px;
}

#header nav a {
    font-size: 16px;
    font-weight: 500;
    color: var(--text-color);
    padding: 10px 0;
    position: relative;
}

#header nav a:before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width 0.3s ease;
}

#header nav a:hover:before,
#header nav a.active:before {
    width: 100%;
}

#header nav a.active {
    color: var(--primary-color);
}

.header-right {
    display: flex;
    align-items: center;
}

.search {
    position: relative;
    margin-right: 20px;
}

.search input {
    width: 180px;
    height: 36px;
    border: 1px solid var(--border-color);
    border-radius: 18px;
    padding: 0 40px 0 15px;
    font-size: 14px;
    transition: all 0.3s ease;
}

.search input:focus {
    outline: none;
    width: 220px;
    border-color: var(--primary-color);
}

.search button {
    position: absolute;
    right: 10px;
    top: 50%;
    transform: translateY(-50%);
    background: transparent;
    border: none;
    cursor: pointer;
}

.search button img {
    width: 16px;
    height: 16px;
}

.language {
    position: relative;
    cursor: pointer;
}

.language .current {
    display: flex;
    align-items: center;
    font-size: 14px;
    color: var(--text-color);
}

.language .current:after {
    content: '';
    display: inline-block;
    margin-left: 5px;
    border-left: 5px solid transparent;
    border-right: 5px solid transparent;
    border-top: 5px solid var(--text-color);
}

.language .lang-options {
    position: absolute;
    top: 100%;
    right: 0;
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 5px 0;
    min-width: 100px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all 0.3s ease;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.language:hover .lang-options {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.language .lang-options a {
    display: block;
    padding: 8px 15px;
    font-size: 14px;
}

.language .lang-options a:hover {
    background-color: var(--light-bg);
}

.language .lang-options a.active {
    color: var(--primary-color);
    font-weight: 500;
}

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 30px;
    height: 20px;
    cursor: pointer;
}

.mobile-menu-btn span {
    display: block;
    height: 2px;
    width: 100%;
    background-color: var(--primary-color);
    transition: all 0.3s ease;
}

@media screen and (max-width: 991px) {
    .mobile-menu-btn {
        display: flex;
    }

    #header nav {
        position: absolute;
        top: 80px;
        left: 0;
        width: 100%;
        background-color: #fff;
        flex-direction: column;
        align-items: stretch;
        padding: 0;
        max-height: 0;
        overflow: hidden;
        transition: all 0.5s ease;
        box-shadow: 0 5px 10px rgba(0, 0, 0, 0.1);
    }

    #header.active nav {
        max-height: 400px;
        padding: 20px 0;
    }

    #header nav ul {
        flex-direction: column;
    }

    #header nav li {
        margin: 0;
    }

    #header nav a {
        display: block;
        padding: 12px 20px;
        border-bottom: 1px solid var(--grey-color);
    }

    #header nav a:before {
        display: none;
    }

    .header-right {
        margin-left: auto;
        margin-right: 20px;
    }

    .search {
        display: none;
    }
}