/* Red border when duplicates exist */
.dup-warning {
    border-color: var(--bs-danger) !important;
    box-shadow: 0 0 0 .25rem rgba(220, 53, 69, .15) !important;
}

/* Duplicate line overlay that sits behind the textarea text */
.dup-overlay {
    position: absolute;
    inset: 0;
    margin: 0;
    pointer-events: none;
    white-space: pre-wrap;
    word-wrap: break-word;

    /* Match textarea padding & font so lines align */
    padding: .375rem .75rem;
    font: inherit;
    line-height: inherit;

    /* Hide text, show only background highlights */
    color: transparent;

    border-radius: .375rem;
    z-index: 0;
}

/* Make textarea render above overlay, but transparent background so highlights show */
#urlsInput {
    position: relative;
    z-index: 1;
    background-color: transparent;
}

/* Highlight for duplicate lines */
.dup-overlay mark {
    background: rgba(220, 53, 69, .20);
    color: transparent;
    padding: 0;
}