Open your css. Paste following code at bottom of stylesheet. Save as an html
<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/lodash.js/2.4.1/lodash.min.js"></script>
<script>
$("script").empty(); //use jQuery remove script element text before analysis
var bootstrapCSS = $("body").text(); //grab all text on the page (all bootstrap css)
bootstrapCSS = bootstrapCSS.replace(
/(/*([^*]|[rn]|(*+([^*/]|[rn])))**+/)|(//.*)/g, ""
); // remove comments from the css
bootstrapCSS = bootstrapCSS.replace(
/(@media.*{)/g, ""
); // remove media query lines up to and including first open brace
bootstrapCSS = bootstrapCSS.replace(
/({[^}]+})/g, ""
); // remove all css in between braces
var res = bootstrapCSS.match(
/([.][w]+([-][w]*)*)/g
); // match .classnames with any number of dashes
res = _.uniq(res); //use lo-dash uniq() method to pull out duplicates
res = res.sort(); //sort alphabetically (not case sensitive, but no real need)
$("body").empty(); //empty the page before redisplay
for (var i = 0; i < res.length; i++) {
$("body").append(res[i]+"<br>"); //append each unique class name back to DOM
}
</script>