Inputmask/css/inputmask.css

span.im-caret {
    animation: 1s blink step-end infinite;
}

span.im-caret-select {
    background-color: rgba(0, 0, 0, 0.25);
}

@keyframes blink {
    from, to {
        border-right-color: black;
    }
    50% {
        border-right-color: transparent;
    }
}

span.im-static {
    color: grey;
}

div.im-colormask {
    display: inline-block;
    border-style: inset;
    border-width: 2px;
    -webkit-appearance: textfield;
    -moz-appearance: textfield;
    appearance: textfield;
}

div.im-colormask > input {
    position: absolute !important;
    display: inline-block;
    background-color: transparent;
    color: transparent;
    caret-color: transparent;
    -webkit-appearance: caret;
    -moz-appearance: caret;
    appearance: caret;
    border-style: none;
    left: 0; /*calculated*/
}

div.im-colormask > input:focus {
    outline: none;
}

div.im-colormask > input::selection{
    background: none;
}
div.im-colormask > input::-moz-selection{
    background: none;
}

div.im-colormask > div {
    color: black;
    display: inline-block;
    width: 100px; /*calculated*/
}