.ux-swatch.ux-swatch__out-of-stock {
    position: relative;
    opacity: 0.35;  
	cursor: default;
	pointer-events: none;
}

.uxx-swatch.ux-swatch__out-of-stock::after {
    content: "✕";              /* the X */
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 16px;
    font-weight: bold;
    color: #d00;               /* red X */
    pointer-events: none;
}