.mobile-overlay {
    position: fixed;
    inset: 0;
    z-index: 200;
    display: none;
    background: var(--surface-overlay, rgba(15, 23, 42, .46));
    backdrop-filter: blur(4px);
}

@media (max-width: 900px) {
    body.sidebar-open .mobile-overlay {
        display: block;
    }
}