Standard 2 column layout in cms 7.1 doesn't use the full width

I'm not sure if this happens in later versions of the cms, but in CMS 7.1 when using 2 column layout, not the full width is used. See the white part in the attached screenshot.

.hippo-editor-field-html .htmlarea .toolbar a.button:hover

{border:1px solid #335500; padding:0; background-image:url(hover.png);}

.hippo-preview-document table

{width: 100%;}

.hippo-editor .hippo-editor-metadata

{width: 25%; background: #f2f2f2; padding: 4px; padding-top: 0px;}