header {
    border-bottom: 1px solid var(--color-divider);
    padding: 20px 0;
    width: 100%;
    background: linear-gradient(to bottom, rgba(0, 0, 0, 0.6), rgba(0, 0, 0, 0.4));
    position: fixed;
    top: 0;
    left: 0;
    z-index: 1000;
}

.header-expand {
    display: flex;
    align-items: center;
    gap: 40px;
}

.main-nav {
    flex: 1;
    display: flex;
    justify-content: center;
}

.main-nav ul {
    display: flex;
    align-items: center;
    gap: 30px;
}

.main-nav li {
    list-style: none;
}

.main-nav a {
    color: var(--color-light);
    text-decoration: none;
    font-size: 16px;
    font-weight: 600;
    transition: color 0.3s ease, transform 0.2s ease;
}

.main-nav a:hover,
.main-nav a:focus {
    color: var(--color-primary);
    transform: translateY(-2px);
}

.btn-toggle {
    display: none;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    color: var(--color-light);
    border: none;
    background-color: var(--color-primary);
    width: 40px;
    height: 40px;
    border-radius: 8px;
    transition: background-color 0.3s ease;
}

.btn-toggle i {
    display: none;
    font-size: 20px;
}

.btn-toggle i.active {
    display: block;
}

@media (max-width: 992px) {
    header {
        padding: 15px;
    }
    .header-expand {
        position: relative;
    }
    .main-nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: var(--color-primary);
        padding: 20px;
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
        transition: max-height 0.3s ease-in-out;
        max-height: 0;
        overflow: hidden;
    }
    .main-nav.show {
        display: block;
        max-height: 300px;
    }
    .main-nav ul {
        flex-direction: column;
        align-items: flex-start;
        gap: 15px;
    }
    .main-nav a {
        font-size: 18px;
        width: 100%;
        padding: 10px;
    }
    .btn-primary {
        display: none;
    }
    .btn-toggle {
        display: flex;
    }
}