Cascading Style Sheets, aka Cascading Style Sheets, is an actively used stylesheet language created in 1996.

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Example code from the Hello World Collection:

/* Hello World in CSS */
body:before {
    content: "Hello World";
}

Example code from Linguist:

/*!
 * Bootstrap v2.3.1
 *
 * Copyright 2012 Twitter, Inc
 * Licensed under the Apache License v2.0
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Designed and built with all the love in the world @twitter by @mdo and @fat.
 */
.clearfix{*zoom:1;}.clearfix:before,.clearfix:after{display:table;content:"";line-height:0;}
.clearfix:after{clear:both;}
.hide-text{font:0/0 a;color:transparent;text-shadow:none;background-color:transparent;border:0;}
.input-block-level{display:block;width:100%;min-height:30px;-webkit-box-sizing:border-box;-moz-box-sizing:border-box;box-sizing:border-box;}
article,aside,details,figcaption,figure,footer,header,hgroup,nav,section{display:block;}
audio,canvas,video{display:inline-block;*display:inline;*zoom:1;}
audio:not([controls]){display:none;}
html{font-size:100%;-webkit-text-size-adjust:100%;-ms-text-size-adjust:100%;}
a:focus{outline:thin dotted #333;outline:5px auto -webkit-focus-ring-color;outline-offset:-2px;}
a:hover,a:active{outline:0;}
sub,sup{position:relative;font-size:75%;line-height:0;vertical-align:baseline;}
sup{top:-0.5em;}
sub{bottom:-0.25em;}
img{max-width:100%;width:auto\9;height:auto;vertical-align:middle;border:0;-ms-interpolation-mode:bicubic;}
#map_canvas img,.google-maps img{max-width:none;}
button,input,select,textarea{margin:0;font-size:100%;vertical-align:middle;}
button,input{*overflow:visible;line-height:normal;}
button::-moz-focus-inner,input::-moz-focus-inner{padding:0;border:0;}
button,html input[type="button"],input[type="reset"],input[type="submit"]{-webkit-appearance:button;cursor:pointer;}
label,select,button,input[type="button"],input[type="reset"],input[type="submit"],input[type="radio"],input[type="checkbox"]{cursor:pointer;}
input[type="search"]{-webkit-box-sizing:content-box;-moz-box-sizing:content-box;box-sizing:content-box;-webkit-appearance:textfield;}
input[type="search"]::-webkit-search-decoration,input[type="search"]::-webkit-search-cancel-button{-webkit-appearance:none;}
textarea{overflow:

Example code from Wikipedia:

body {
   overflow: hidden;
   background: #000000;
}
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Last updated February 11th, 2019