Below is an MWE.
%---------------------------------------------------------------------
% PACKAGES AND OTHER DOCUMENT CONFIGURATIONS
%---------------------------------------------------------------------
\documentclass[twoside]{article}
\usepackage{lipsum,xcolor}
\usepackage[hmarginratio=1:1,top=32mm,columnsep=20pt]{geometry} % Document margins
\usepackage{multicol} % Used for the two-column layout of the document
\usepackage{titlesec} % Allows customization of titles
\titleformat{\section}[block]{\large\scshape}{}{0pt}{\colorsection}{}
\renewcommand\thesection{}
\newcommand{\colorsection}[1]{\colorbox{blue!20}{\parbox{\columnwidth}{\thesection \centering #1}}}
\usepackage{fancyhdr} % Headers and footers
\pagestyle{fancy} % All pages have headers and footers
%----------------------------------------------------------------------------------------
% TITLE SECTION
%----------------------------------------------------------------------------------------
\title{\vspace{-15mm}\fontsize{24pt}{10pt}\selectfont\textbf{A Minimum Working Example}} % Article title
\author{}
\date{}
%----------------------------------------------------------------------------------------
\begin{document}
\maketitle % Insert title
\thispagestyle{fancy} % All pages have headers and footers
%----------------------------------------------------------------------------------------
% ARTICLE CONTENTS
%----------------------------------------------------------------------------------------
\begin{multicols}{2} % Two-column layout throughout the main article text
\section*{Introduction}
\lipsum[2-3] % Dummy text
%------------------------------------------------
\section*{Discussion}
\lipsum[7] % Dummy text
\end{multicols}
\end{document}
As you can see that there is a minor difference in width of the column and the width of the column text itself. How can I correct the discrepancy?


24ptfont. Use something like\LARGEor\huge, or\Huge, depending on what's closest. See What point (pt) font size are\Largeetc.? for a discussion on font sizes that are based on your default document class choice (10pt in your case). – Werner Dec 06 '15 at 07:53\fontsize{24pt}{10pt}\selectfontwork ? I guess the O.P. uses vector fonts, as every one does nowadays. – Bernard Dec 06 '15 at 11:24