Align shaded box to top of page

Question

I have a page that has a shaded box at the top. How do I get the shaded box to align with the top of the page frame? There's a bit of a gap. My code:

\documentclass[10pt]{book}
\usepackage[showframe]{geometry}
\usepackage[x11names]{xcolor}
\usepackage{framed}
\colorlet{shadecolor}{LavenderBlush2}
\usepackage{lipsum}
\begin{document}
\setlength{\OuterFrameSep}{0pt}
\begin{shaded*}
\lipsum[1]
\end{shaded*}
\vfill
\begin{shaded*}
\lipsum[1]
\end{shaded*}
\end{document}

results in

In another question (Align shaded box to bottom of page), it has been suggested to set OuterFrameSep to 0 in order to remove the vertical space before and after the framed environment. That does seem to work for after the framed environment, but not before.

Answer 1

Try the following, it may work for you too:

\documentclass[10pt]{book}
\usepackage{geometry}
\usepackage[x11names]{xcolor}
\usepackage{framed}
\colorlet{shadecolor}{LavenderBlush2}
\setlength{\OuterFrameSep}{0pt}

\usepackage{etoolbox}                           % <---
\BeforeBeginEnvironment{shaded*}{\topskip=0pt}  % <---
\AfterEndEnvironment{shaded*}{\topskip=10pt}    % <---
\usepackage{lipsum}
\usepackage{graphicx}
%---------------- Show page layout. Don't use in a real document!
\usepackage{showframe}
\renewcommand\ShowFrameLinethickness{0.15pt}
\renewcommand*\ShowFrameColor{\color{red}}
%---------------------------------------------------------------%

\begin{document}
\begin{shaded*}
\lipsum[1]
\end{shaded*}

\vfill
\begin{shaded*}
\lipsum[1]
\end{shaded*}
\clearpage
\begin{figure}[ht]
\includegraphics[width=\linewidth]{example-image-duck}
\end{figure}
\section{title}\lipsum
\end{document}