Move to a theme that more closely matches what was there before.

experimental/webtry/res/js/webtry.js

 /**
  * Common JS that talks XHR back to the server and runs the code and receives
  * the results.
  */
 
 /**
  * A polyfill for HTML Templates.
  *
  * This just adds in the content attribute, it doesn't stop scripts
  * from running nor does it stop other side-effects.
@@ skipping 157 matching lines @@
     var embedButton = document.getElementById('embedButton');
     var code = document.getElementById('code');
     var output = document.getElementById('output');
     var stdout = document.getElementById('stdout');
     var img = document.getElementById('img');
     var tryHistory = document.getElementById('tryHistory');
     var parser = new DOMParser();
     var tryTemplate = document.getElementById('tryTemplate');
 
     var editor = CodeMirror.fromTextArea(code, {
-      theme: "ambiance",
+      theme: "default",
       lineNumbers: true,
       matchBrackets: true,
       mode: "text/x-c++src",
       indentUnit: 4,
     });
 
     // Match the initial textarea size.
     editor.setSize(editor.defaultCharWidth() * code.cols,
                    editor.defaultTextHeight() * code.rows);
 
@@ skipping 147 matching lines @@
 
 
     // Add the images to the history if we are on a workspace page.
     if (tryHistory && history) {
       for (var i=0; i<history.length; i++) {
         addToHistory(history[i].hash, '/i/'+history[i].hash+'.png');
       }
     }
 
 })(workspaceName);