#custom-caret {
    position: fixed;
    left: 0;
    top: 0;
    width: 2px;
    height: 1em;
    display: none;
    pointer-events: none;
    z-index: 2;
    forced-color-adjust: none;
    animation: caret-blink 1s steps(1, end) infinite;
}

#caret-measure {
    position: fixed;
    visibility: hidden;
    pointer-events: none;
}

@keyframes caret-blink {
    0%, 49% { opacity: 1; }
    50%, 100% { opacity: 0; }
}