I want to insert a paragraph or possibly even a box with a background color into a list that uses the whole `\textwidth`. Something like this:

```
1st item 
   a subitem 1
   b subitem 2

2nd item
   a subitee

\begin{use the full width}
   [ Here the text should use the full text width ignoring the list indent]
\end{use the full width}
   b subitem
3rd item

```

The list is a normal enumerate.