Wait you have access to pure HTML? If that's the case just put this above your doctype, absolute first line of code (Theoretically bad practice):
<iframe id="iframe" src="http://dl.dropbox.com/u/56104169/WebTest/index.html" width="1150" height="300" scrolling="no" frameborder="0" ></iframe>
And remove the following:
<div class='navbar section' id='navbar'><div class='widget HTML' id='HTML5'>
<h2 class='title'>Construct2</h2>
<div class='widget-content'>
<div class='clear'></div>
<span class='widget-item-control'>
<span class='item-control blog-admin'>
<a class='quickedit' href='//www.blogger.com/rearrange?blogID=1649094877974200757&widgetType=HTML&widgetId=HTML5&action=editWidget§ionId=navbar' onclick='return _WidgetManager._PopupConfig(document.getElementById("HTML5"));' target='configHTML5' title='Edit'>
<img alt='' height='18' src='http://img1.blogblog.com/img/icon18_wrench_allbkg.png' width='18'/>
</a>
</span>
</span>
<div class='clear'></div>
</div>
The CSS will do all the positioning you need.