     equals: (opts)->
       @button({
         value: '='
-        class: 'math-button operation'
+        class: 'math-button operation equal'
       }, opts)
 
     clear: (opts)->

        class: 'math-button other square'
      }, opts)

    square_root: (opts)->
      @button({
        value: 'squareroot'
        label: '&radic;<span>&#8212;</span>'
        class: 'math-button other square-root'
      }, opts)

    lparen: (opts)->
      @button({

      @button({
        value: 'fn'
        label: '&fnof;'
        class: 'math-button other function'
      }, opts)

    button: (type_opts, opts={})->
      ui_elements.button_builder.build(
        _.extend({}, type_opts, @opts, opts))

  class_mixer(ButtonBuilder)

