Align text in paracol environment on title page

Question

I want to make the title next to the column seperator. I couldn't manage it with parindent. I have added a minaimal working code below.

    \documentclass{book}
    \usepackage{geometry}
    \usepackage{paracol}
    \usepackage{polyglossia}
    \usepackage{fontspec}
    \usepackage{float}
    \usepackage{bidi}
\geometry{ a4paper, left=10mm, right=10mm, top=20mm, bottom=18mm }
\setlength{\columnseprule}{2.4pt}
\setotherlanguage{arabic}

\title{
\columnratio{0.35}
\begin{paracol}{2}
\Huge
\setRTL
\setmainfont{Scheherazade New}
\textarabic{{ابت ايت}}
\switchcolumn 
\setLTR
\Huge\bf~\\
ABC ABC
\end{paracol}
\vfill}

\author{ِABC\\ِAbc}

\begin{document}
\maketitle
\end{document}

Answer 1

I don't know what you want to achieve exactly, but the reason for the space is that the text in both columns is centered, since the text on the title page is centered by default and this also affects the text in the columns. Hence, you need to state \raggedright or \raggedleft in the relevant columns to have the text right- or left aligned.

\documentclass{book}
\usepackage{geometry}
\usepackage{paracol}
\usepackage{polyglossia}
\usepackage{fontspec}
\geometry{a4paper, left=10mm, right=10mm, top=20mm, bottom=18mm}
\setlength{\columnseprule}{2.4pt}
\setlength{\columnsep}{3em}
\setotherlanguage{arabic}
\newfontfamily\arabicfont[Script=Arabic]{Amiri}
\title{
\begin{paracol}{2}
\setRTL\raggedleft\Huge\bfseries
\textarabic{ابت ايت}
\switchcolumn 
\setLTR\raggedright\Huge\bfseries
ABC ABC
\end{paracol}
}
\author{}
\begin{document}
\maketitle
\end{document}

There are a few other things you should consider:

• Do not use \bf, but use \bfseries or \textbf{} instead. Learn why ...
• Do not place \setmainfont inside a macro. Instead, set the main fonts you want to use in the preamble at document level. You can automatically let LaTeX switch between the fonts by defining a font family named \arabicfont.
• Remove the arabic diacritic marks from the \author macro.