gistfile1.txt

// View

  ul.tabs
    li.selected
      a(x-bind='click: selectTab') Tab 1
    li
      a(x-bind='click: selectTab') Tab 2
    li
      a(x-bind='click: selectTab') Tab 3
  ul
    li.selected
      | First
    li
      | Second
    li
      | Third

// Event-handler

  selectTab = (e, el) ->
    $el = $(el)
    $el.parent().siblings().removeClass('selected').end().addClass('selected')
    $el.closest('.tabs').next().children().removeClass('selected').eq( $el.parent().index() ).addClass('selected')

// CSS

.tabs
  +horizontal-list
  > .selected
    font-weight: bold
  & + ul    
    > li
      display: none
      &.selected
        display: block