.extension-windowsNavigator-window-tooltip {
    color: #fefefe;
    background: rgba(0,0,0,0.8);
    border: 1px solid rgba(128,128,128,0.40);
    border-radius: 10px;
    font-size: 16px;
    padding: 2px 8px;
    -shell-caption-spacing: 4px;
}