css:
  #editor { 
      position: absolute;
      top: 0;
      right: 0;
      bottom: 0;
      left: 0;
  }

.row
  .span6
    font style="font-size: 27pt" Editing #{params[:filename]}
  .span6
    span.pull-right
      | Theme: 
      select id="theme" size="1" onchange="setTheme();" onkeyup="setTheme();"
        optgroup label="Bright"
          option value="ace/theme/chrome" Chrome
          option value="ace/theme/clouds" Clouds
          option value="ace/theme/crimson_editor" Crimson Editor
          option value="ace/theme/dawn" Dawn
          option value="ace/theme/dreamweaver" Dreamweaver
          option value="ace/theme/eclipse" Eclipse
          option value="ace/theme/github" GitHub
          option value="ace/theme/solarized_light" Solarized Light
          option value="ace/theme/textmate" TextMate
          option value="ace/theme/tomorrow" Tomorrow
          option value="ace/theme/xcode" XCode
        optgroup label="Dark"
          option value="ace/theme/ambiance" Ambiance
          option value="ace/theme/chaos" Chaos
          option value="ace/theme/clouds_midnight" Clouds Midnight
          option value="ace/theme/cobalt" Cobalt
          option value="ace/theme/idle_fingers" idleFingers
          option value="ace/theme/kr_theme" krTheme
          option value="ace/theme/merbivore" Merbivore
          option value="ace/theme/merbivore_soft" Merbivore Soft
          option value="ace/theme/mono_industrial" Mono Industrial
          option value="ace/theme/monokai" Monokai
          option value="ace/theme/pastel_on_dark" Pastel on dark
          option value="ace/theme/solarized_dark" selected="selected" Solarized Dark
          option value="ace/theme/terminal" Terminal
          option value="ace/theme/tomorrow_night" Tomorrow Night
          option value="ace/theme/tomorrow_night_blue" Tomorrow Night Blue
          option value="ace/theme/tomorrow_night_bright" Tomorrow Night Bright
          option value="ace/theme/tomorrow_night_eighties" Tomorrow Night 80s
          option value="ace/theme/twilight" Twilight
          option value="ace/theme/vibrant_ink" Vibrant Ink

.row
  .span12
    div id="editor" style="width: 100%; height: 1000px; position: relative;"
      p Loading, please wait..
    
.row.text-center style="margin-top: 10px"
  .span4
    a.btn.btn-large.btn-warning href="" Cancel
  .span4
    a.btn.btn-large.btn-success href="" Save Changes
  .span4
    a.btn.btn-large.btn-info href="" Save and Finish Editing
    
    
script src="http://rawgithub.com/ajaxorg/ace-builds/master/src-noconflict/ace.js" type="text/javascript" charset="utf-8"
javascript:

  function setTheme(name) {
    editor.setTheme($('#theme').val());
  }

  var editor = {};

  $(document).ready(function() {
    $.get("#{@file_url}", function (response) {
      $("#editor").text(response);
      
      editor = ace.edit("editor");
      setTheme();
      editor.getSession().setMode("ace/mode/html");
      editor.setFontSize(14);
      editor.setShowPrintMargin(false);
    });
  });