/* --- Header --- */
.site-header {
    background-color: var(--surface-color); /* Dark surface background */
    box-shadow: 0 2px 5px rgba(0,0,0,0.3); /* Slightly stronger shadow for dark */
    height: var(--header-height);
    position: sticky; /* Changed from fixed to sticky */
    top: 0;
    left: 0;
    width: 100%;
    z-index: 10000; /* Increased significantly again for fixed position */
    transition: top 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
}

.site-header.scrolled {
}

.header-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    /* Assuming .container utility class is used within header for max-width */
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 1rem; /* Match container padding */
}

.logo img {
    max-height: 40px; /* Adjust as needed */
    width: auto;
}

.main-navigation {
    display: flex;
    align-items: center;
}

.nav-menu {
    display: flex;
    gap: 1.5rem;
    list-style: none; /* Ensure list style is none */
    margin: 0; /* Ensure no default margin */
    padding: 0; /* Ensure no default padding */
}

.nav-menu li a {
    color: var(--dark-color); /* Light text */
    font-weight: 600;
    padding: 0.5rem 0;
    position: relative;
    text-decoration: none;
}

.nav-menu li a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--tertiary-accent);
    transition: width 0.3s ease;
}

.nav-menu li a:hover::after,
.nav-menu li a.active::after {
    width: 100%;
}

.nav-menu li a.active {
    color: var(--primary-color); /* Accent/Link Color */
}

.menu-toggle {
    display: none; /* Hidden by default */
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--dark-color); /* Light text */
}

.header-social-icons {
    display: flex;
    gap: 1rem;
    margin-left: 1.5rem; /* Space between nav and social icons */
}

.header-social-icons a {
    color: var(--secondary-color);
    font-size: 1.2rem;
}
.header-social-icons a:hover {
    color: var(--primary-color); /* Using coral for hover on aqua icons for consistency with buttons */
    text-decoration: none;
}

/* --- Responsive Header Styles --- */
@media (max-width: 768px) {
    .nav-menu {
        display: none; /* Hide menu by default */
        position: absolute;
        top: var(--header-height); /* Position below header */
        left: 0;
        width: 100%;
        background-color: var(--surface-color); /* Dark surface */
        flex-direction: column;
        padding: 1rem 0;
        box-shadow: 0 5px 10px rgba(0,0,0,0.3); /* Stronger shadow */
        gap: 0;
        z-index: 999; /* Below header */
    }
    .nav-menu.toggled {
        display: flex; /* Show when toggled */
    }
    .nav-menu li {
        width: 100%;
        text-align: center;
    }
    .nav-menu li a {
        display: block;
        padding: 0.8rem 1rem;
        border-bottom: 1px solid var(--border-color); /* Darker border */
        color: var(--dark-color); /* Ensure text is light */
    }
    .nav-menu li:last-child a {
        border-bottom: none; /* Remove border from last item */
    }
    .nav-menu li a::after {
        display: none; /* Remove underline effect on mobile */
    }
    .nav-menu li a.active {
        background-color: #325F5F; /* Slightly Lighter Secondary Background */
        color: #FFFFFF; /* Heading Text Color */
    }
    .menu-toggle {
        display: block; /* Show hamburger */
    }
    .header-social-icons {
        display: none; /* Hide social icons in header on small screens */
    }
}