.unselectable {
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

span::before {
  content: attr(data-unselectable);
}

.highlight {
    position: relative;
}

.highlight-copy-btn {
    position: absolute;
    bottom: 7px;
    right: 7px;
}