.rechnungen-button {
    background-image: url('images/invoice_icon.svg');
    background-size: 16px 16px;
    background-repeat: no-repeat;
    background-position: center;
    padding-left: 24px; /* Adjust padding to accommodate icon */
    background-color: transparent;
}

.rechnungen-button:hover {
    background-color: #f0f0f0; /* Optional: change background on hover */
}

.menu a.rechnungen-button::before {
    font-family: 'Font Awesome 5 Free';
    content: "\f570"; /* FontAwesome icon code */
    font-weight: 900; /* Required for solid icons */
    margin-right: 5px;
}