SharePoint Rich text editor width 100%

I’ve been looking for this for a while: how can you make the built-in Rich Text editor field in SharePoint to adjust its width to its parent container.
To be completely clear, we’re talking about this control:

The Width property does not work for this control in SharePoint 2010.

The following CSS makes it so.

iframe[title="Rich Text Editor"]
{
    width: 100% !important;
}

td.ms-authoringcontrols table.ms-rtetoolbarmenu
{
    width: 100% !important;
}

I’ve found some help from Zach’s blog, but added the second CSS rule to also resize the toolbar, which looks a lot nicer: