Variant Buttons Custom Color

To change Variant Color Buttons to Custom Color, you can use this code to Custom CSS box

label[for*="Color-BLACK"] {
    background-color: #000 !important;
    color: #fff !important
}

label[for*="Color-BLUE"] {
    background-color: #5dc1f3 !important;
    color: #fff !important
}

label[for*="Color-RED"] {
    background-color: red !important;
    color: #fff !important
}

label[for*="Color-ORANGE"] {
    background-color: orange !important;
    color: #fff !important
}

label[for*="Color-GREEN"] {
    background-color: green !important;
    color: #fff !important
}

label[for*="Color-CHAMPAGNE"] {
    background-color: #cdbcaf !important
}

(this is just an example code, you can do similar for your case)