- Store HTML for modal window inside an invisible <div> element instead
of inside the <button> element's value attribute
- Mark history.detailed_msg as safe as it is already manually run
through the template engine beforehand and would be broken if escaped
a second time
As the URL here is contructed from Flask's "url_for" which already
takes the script root into account, we do not need to add it here
explicitly. This would result in a duplicate script root otherwise.
