.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: color-mix(in srgb, var(--bg) 82%, transparent);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--border);
}

.navbar {
    max-width: 1100px;
    margin: 0 auto;
    padding: 1rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    text-decoration: none;
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 1.15rem;
    color: var(--text);
}

.brand-mark {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    border-radius: 9px;
    color: #fff;
    background: linear-gradient(135deg, var(--accent), var(--accent-3));
    font-weight: 700;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 1.75rem;
}

.nav-links a {
    text-decoration: none;
    font-weight: 500;
    font-size: 0.98rem;
    color: var(--text-muted);
    position: relative;
    padding-bottom: 3px;
    transition: color 0.2s ease;
}

.nav-links a::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    bottom: -2px;
    height: 2px;
    background: linear-gradient(90deg, var(--accent), var(--accent-3));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.25s ease;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--text);
}

.nav-links a:hover::after,
.nav-links a.active::after {
    transform: scaleX(1);
}

.nav-icon-link {
    font-size: 1.1rem;
    display: inline-flex;
}

.nav-icon-link::after { display: none; }

.theme-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2.25rem;
    height: 2.25rem;
    border-radius: 999px;
    border: 1px solid var(--border);
    background: var(--bg-elevated);
    color: var(--text);
    cursor: pointer;
    transition: border-color 0.2s ease, transform 0.2s ease;
}

.theme-toggle:hover { border-color: var(--accent); transform: rotate(-8deg); }

.theme-icon-light { display: none; }
:root[data-theme="dark"] .theme-icon-light { display: inline-block; }
:root[data-theme="dark"] .theme-icon-dark { display: none; }

.nav-toggle {
    display: none;
    width: 2.25rem;
    height: 2.25rem;
    border-radius: 9px;
    border: 1px solid var(--border);
    background: var(--bg-elevated);
    color: var(--text);
    font-size: 1rem;
    cursor: pointer;
}

@media (max-width: 720px) {
    .nav-toggle { display: inline-flex; align-items: center; justify-content: center; }

    .nav-links {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        align-items: flex-start;
        gap: 1.1rem;
        padding: 1.25rem 1.5rem 1.75rem;
        background: var(--bg-elevated);
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow);
        transform: translateY(-8px);
        opacity: 0;
        pointer-events: none;
        transition: transform 0.2s ease, opacity 0.2s ease;
    }

    .nav-links.open {
        transform: translateY(0);
        opacity: 1;
        pointer-events: auto;
    }
}