Is there a trick to not apply the leftoffset to the header of a defineenumeration?

MWE:

\definetextbackground
  [textFrameEx]
  [
    frame=off,
    framecolor=darkgreen,
    rulethickness=2ex,
    background=,
    location=paragraph,
    leftoffset=2.25ex,
    rightoffset=2.25ex,
    after={\hrule}
  ]

\defineenumeration
  [example]
  [
    text=Example,
    headalign=middle,
    headcolor=white,
    headcommand={\inframed[background=color,backgroundcolor=darkgreen,width=\textwidth]},
    number=no,
    before={%
      \starttextbackground[textFrameEx]
    },
    after={%
      \stoptextbackground%
    },
  ]

\starttext

\startexample
    Blablabla
\stopexample

\stoptext