yotti popup overlay color

Hello,

the popup background is default rgba (0,0,0, .7.
How and where can I change this in e.g. rgba (255,255,255, .;

.yottie-popup .yottie-popup-overlay {
position: absolute;
visibility: hidden;
top: 0;
right: 0;
bottom: 0;
left: 0;
background: rgba(0,0,0,.7);
transition: .25s ease;
}