Font weight when active - CSS

Question

Currently I am trying to make the selected list item STAY bold after selected and go back to normal after a different item is selected. basically I want a "currently selected tab". is there a way I can do this with css or do I need Javascript? Here is my code ->

CSS: (using SASS)

   .setup-nav {
  float: left;
  position: relative;
  width: 20%;
  padding-right: 20px;
  box-sizing: border-box;

  font-size: 18px;
  color: $base-link-color;
  text-align: left;

  li {
    border-top: none;
    border-bottom: none;

    &.active {
      font-weight: bold;
    }
  }

HTML:

<ul class="setup-nav">
  <li><a href="#install-http">HTTP</a></li>
  <li><a href="#install-email">Email</a></li>
  <li><a href="#install-ruby">Ruby</a></li>
  <li><a href="#install-python">Python</a></li>
</ul>

Hopefully there is an easy way to do this.

Answer 1

Using jQuery:

$(".setup-nav").on( "click", "li", function(){ // attach to Click event
    $(".setup-nav li.active").removeClass("active"); // reset all <li> to no active class
    $(this).addClass("active"); // add active class to this <li> only
});

http://api.jquery.com/on/ reference for use of .on()

http://api.jquery.com/addClass/ reference for use of .addClass()

Someone may come along with pure JavaScript answer (no jQuery library use) if you prefer that approach.