pre[data-number] {
    position: relative;
    padding: 1em 0 1em 3em;
}

.redesign pre[data-number] {
    padding-left: 30px;
}

.line-number {
    position: absolute;
    left: 0;
    right: 0;
    padding: inherit 0;
    margin-top: 1em; /* Same as .prism’s padding-top */
    background: transparent;
    pointer-events: none;
    line-height: inherit;
    white-space: pre;
}

.line-number:before, .line-number[data-end]:after {
    content: attr(data-start);
    position: absolute;
    top: .4em;
    left: .6em;
    min-width: 1em;
    padding: 0 .5em;
    color: #999;
    font: bold 65%/1.5 sans-serif;
    text-align: center;
    vertical-align: .3em;
    border-radius: 999px;
    text-shadow: none;
    border: 0;
}

.line-number[data-end]:after {
    content: attr(data-end);
    top: auto;
    bottom: .4em;
}
