# Adding chapterheadendvskip with “phantom” chapterprefix in KOMA Script (scrreprt) with grid layout (grid.sty)

First of all, I apologize if this question is too localised, my explanation is too vague (and perhaps irrelevant) and the given MWE is too messed up.

I am trying to use grid layout provided by grid.sty using document class scrreprt. I declare in my preamble \usepackage[fontsize=12pt,baseline=28.8pt,lines=25]{grid} so it is 12pt/28.8pt or doublespaced.

I use twolinechapter option in scrreprt, and change the beforeskip to 0\baselineskip and afterskip to 1\baselineskip using \RedeclareSectionCommand and make it centred.

Because I also have Unnumbered Chapter and I wish to make it aligned vertically to chaptertitle instead of chapterprefix of Numbered Chapter, I use 'phantom' chapterprefix below:

\makeatletter
\renewcommand\chapterlineswithprefixformat[3]{%
\ifstrempty{#2}
{%
{\usekomafont{#1prefix}{\strut%
\setlength{\@tempskipa}{0\baselineskip}
}
{%
\MakeUppercase{#2}%
}%
\MakeUppercase{#3}
}%
\makeatother


But then, my References shall be 12pt, singlespaced. Chapters and Unnumbered Chapters shall be typeset in 14pt. So I do

\makeatletter
\renewcommand\large{\@setfontsize\large{14pt}{28.8pt}}
\newcommand\bibnormalsize{\@setfontsize\normalsize{12pt}{14.4pt}}
\makeatother
\renewcommand\bibfont{\bibnormalsize}


The problem is, while the chaptertitle REFERENCES sits correctly on the grid and aligns with chaptertitle of Numbered Chapter, the first line of referenced items on my References is "raised" (i.e. not aligned to the first line of the paragraph under Chapter 1), probably because the leading is 14.4pt instead of 28.8pt.

I, therefore, think that I need to add some chapterheadendvskip for Unnumbered Chapter to lower the items on my References, but I do not know how.

My (not so) minimum (and very messed up) working example is given below:

%% Preamble %%
\usepackage[a4paper,left=40mm,right=25mm,top=25mm,bottom=25mm,footskip=10mm]{geometry}
\usepackage{lipsum}
\usepackage[fontsize=12pt,baseline=28.8pt,lines=25]{grid}
\usepackage[authordate,backend=biber]{biblatex-chicago}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@Book{test1,
author    = {Goossens, Michel and Mittelbach, Frank and Samarin, Alexander},
title     = {The LaTeX Companion},
year      = {1994},
}
\end{filecontents}

\makeatletter
\renewcommand\large{\@setfontsize\large{14pt}{28.8pt}}
\newcommand\bibnormalsize{\@setfontsize\normalsize{12pt}{14.4pt}}
\makeatother

% Strip skips before Chapter and between chapterprefix and chaptername and centre the Chapter
\RedeclareSectionCommand[
beforeskip = 0\baselineskip,
afterskip =1\baselineskip
]{chapter}
\renewcommand*\raggedchapter{\centering}

% Make serif all text on documents, set Chapter to large font (14pt/28.8pt) and Section to normalsize.
\setkomafont{chapter}{\large}
\setkomafont{chapterprefix}{\large}
\setkomafont{section}{\normalsize}

% Raise the chaptertitle .5\baselineskip
\renewcommand*{\chapterformat}{%
\chapappifchapterprefix{\nobreakspace}\thechapter\autodot%
\IfUsePrefixLine{%
\par\nobreak\vspace{-\parskip}\vspace{-.5\baselineskip}%
}{\enskip}%
}

% Phantom chapterprefix for Unnumbered Chapter (Abstract, Bibliography}
\makeatletter
\renewcommand\chapterlineswithprefixformat[3]{%
\ifstrempty{#2}
{%
{\usekomafont{#1prefix}{\strut%
\setlength{\@tempskipa}{0\baselineskip}%
}
{%
\MakeUppercase{#2}%
}%
\MakeUppercase{#3}
}%
\makeatother

\parindent=2em
\setlength\bibhang{1.5em}
\renewcommand\bibfont{\bibnormalsize}

%% Document Parts %%
\begin{document}
\chapter{Introduction}
This is short introduction to the Chapter, only a paragraph or two, before the Sections kick in.
\section{Background}
\lipsum[2].
Random citation here, nothing too fancy \parencite{test1}. \lipsum[4]
\printbibliography[title={REFERENCES}]
\end{document}


I got the answer from Reduce vertical space after list of algorithms' title, which suggests to modify the appearance of the References (in the link, List of Algorithms) locally, using:

\begingroup
\renewcommand*{\chapterheadstartvskip}{\vspace*{size}} % not applicable for my case.

\begingroup