.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    border-bottom: 1px solid var(--border);
    background: rgba(15, 22, 33, 0.8);
    backdrop-filter: blur(14px);
}

.site-header--admin { background: rgba(30, 41, 59, 0.85); }

.site-navigation {
    min-height: 64px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.site-header--admin .site-navigation { padding: 0 1.75rem; }

.site-brand {
    display: flex;
    align-items: center;
    gap: 0.7rem;
    color: var(--text);
    font-weight: 800;
    font-size: 1.2rem;
    letter-spacing: -0.02em;
    text-decoration: none;
}

.site-header--admin .site-brand { font-size: 1.05rem; font-weight: 600; }

.site-brand__mark {
    width: 36px;
    height: 36px;
    display: grid;
    place-items: center;
    border-radius: 10px;
    background: linear-gradient(135deg, #0ea5e9, #6366f1);
    box-shadow: 0 4px 14px rgba(14, 165, 233, 0.35);
}

.site-header--admin .site-brand__mark {
    width: 34px;
    height: 34px;
    border-radius: 8px;
    background: linear-gradient(135deg, #3b82f6, #8b5cf6);
    box-shadow: none;
    color: #fff;
    font-weight: 700;
}

.site-navigation__user { margin-left: auto; color: var(--muted); font-size: 0.9rem; }
.site-navigation__user strong { color: var(--text); }

.navigation-links { display: flex; align-items: center; gap: 0.35rem; }
.navigation-links a {
    padding: 0.4rem 0.85rem;
    border-radius: 8px;
    color: var(--muted);
    font-size: 0.875rem;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.15s;
}
.navigation-links a:hover,
.navigation-links a[aria-current="page"] { color: var(--text); background: rgba(56, 189, 248, 0.08); }
.site-header--admin .navigation-links a:hover,
.site-header--admin .navigation-links a[aria-current="page"] { background: rgba(51, 65, 85, 0.6); }
.site-header--admin .navigation-links a.logout:hover { color: #fca5a5; background: rgba(239, 68, 68, 0.12); }

.navigation-toggle {
    display: none;
    width: 2.5rem;
    height: 2.5rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: transparent;
    color: var(--text);
    cursor: pointer;
}
.navigation-toggle__icon,
.navigation-toggle__icon::before,
.navigation-toggle__icon::after {
    width: 1.15rem;
    height: 2px;
    display: block;
    background: currentColor;
    content: '';
    transition: transform 0.15s ease;
}
.navigation-toggle__icon { position: relative; margin: auto; }
.navigation-toggle__icon::before { position: absolute; transform: translateY(-6px); }
.navigation-toggle__icon::after { position: absolute; transform: translateY(6px); }
.navigation-toggle[aria-expanded="true"] .navigation-toggle__icon { background: transparent; }
.navigation-toggle[aria-expanded="true"] .navigation-toggle__icon::before { transform: rotate(45deg); }
.navigation-toggle[aria-expanded="true"] .navigation-toggle__icon::after { transform: rotate(-45deg); }

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

@media (max-width: 600px) {
    .site-navigation { min-height: 56px; position: relative; }
    .site-header--admin .site-navigation { padding: 0 1rem; }
    .site-navigation__user { display: none; }
    .navigation-toggle { display: grid; place-items: center; margin-left: auto; }
    .navigation-links {
        display: none;
        position: absolute;
        top: calc(100% - 1px);
        right: 0;
        left: 0;
        flex-direction: column;
        align-items: stretch;
        gap: 0.2rem;
        padding: 0.75rem 1rem 1rem;
        border-bottom: 1px solid var(--border);
        background: #0f1621;
        box-shadow: 0 12px 20px rgba(0, 0, 0, 0.2);
    }
    .site-header--admin .navigation-links { background: #1e293b; }
    .navigation-links.is-open { display: flex; }
    .navigation-links a { padding: 0.65rem 0.85rem; }
}