/* 导航栏样式 */
.nav-wrapper {
    background: white;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    left: 0;
    right: 0;
    z-index: 9999;
    width: 100%;
    border-bottom: 1px solid rgba(0,0,0,0.1);
}

.main-nav {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 0;
}

.nav-item {
    position: relative;
    padding: 1rem 1.5rem;
    cursor: pointer;
}

.nav-item > a {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9rem;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    display: flex;
    align-items: center;
    gap: 5px;
}

.nav-item > a:after {
    content: '▾';
    font-size: 0.8rem;
    transition: transform 0.3s ease;
}

.nav-item:hover > a:after {
    transform: rotate(180deg);
}

.nav-item:hover > a {
    color: var(--primary-color);
}

.nav-item::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 3px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

.nav-item:hover::before {
    width: 80%;
}

.dropdown {
    position: absolute;
    top: 100%;
    left: 0;
    background: white;
    min-width: 250px;
    box-shadow: 0 8px 16px rgba(0,0,0,0.1);
    border-radius: var(--border-radius);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all 0.3s ease;
    padding: 0.8rem 0;
    border: 1px solid rgba(0,0,0,0.1);
}

.nav-item:hover .dropdown {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-item {
    display: flex;
    align-items: center;
    padding: 0.8rem 1.5rem;
    color: var(--text-color);
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.3s ease;
    white-space: nowrap;
    position: relative;
    gap: 10px;
}

.dropdown-item:before {
    content: '';
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--primary-color);
    opacity: 0;
    transition: all 0.3s ease;
}

.dropdown-item:hover:before {
    opacity: 1;
}

.dropdown-item:hover {
    background: var(--background-color);
    color: var(--primary-color);
    padding-left: 2rem;
}

@media (max-width: 768px) {
    .main-nav {
        flex-direction: column;
        padding: 0;
    }

    .nav-item {
        width: 100%;
        text-align: center;
        border-bottom: 1px solid rgba(0,0,0,0.1);
    }

    .nav-item > a {
        justify-content: center;
    }

    .nav-item:last-child {
        border-bottom: none;
    }

    .nav-item::before {
        display: none;
    }

    .dropdown {
        position: static;
        width: 100%;
        box-shadow: none;
        display: none;
        border: none;
        background: var(--background-color);
        transform: none;
    }

    .nav-item:hover .dropdown {
        display: block;
    }

    .dropdown-item {
        padding: 1rem 1.5rem;
        justify-content: center;
    }

    .dropdown-item:hover {
        background: white;
    }
}