prismjs/plugins/line-numbers/prism-line-numbers.min.css

pre[class*=language-].line-numbers{position:relative;padding-left:3.8em;counter-reset:linenumber}pre[class*=language-].line-numbers>code{position:relative;white-space:inherit}.line-numbers .line-numbers-rows{position:absolute;pointer-events:none;top:0;font-size:100%;left:-3.8em;width:3em;letter-spacing:-1px;border-right:1px solid #999;-webkit-user-select:none;-moz-user-select:none;-ms-user-select:none;user-select:none}.line-numbers-rows>span{display:block;counter-increment:linenumber}.line-numbers-rows>span:before{content:counter(linenumber);color:#999;display:block;padding-right:.8em;text-align:right}