How to replicate this title and abstract layout

Question

I would like to replicate this title and abstract layout. I'm using \documentclass[a4paper, twocolumn]{article} as class.

I've tried with \flushleftenvironment, but there's no way to add a background color.

Thanks in advance to all the answers.

Edit: Here my code

\documentclass[twocolumn]{article} 
\usepackage[]{geometry} 
\usepackage{lipsum} 
\usepackage{color}

\begin{document}

\twocolumn[
\begin{@twocolumnfalse}

    \begin{flushleft}
        \fontsize{20pt}\selectfont\color{black}\textbf{Title}
    \end{flushleft}

    \hrule

    \begin{flushleft}
        \fontsize{12pt}\selectfont\color{black}\textbf{First Author}
    \end{flushleft}         

\end{@twocolumnfalse}]

\tableofcontents

\section{Introduction}
    \lipsum[1] 
\end{document}

Answer 1

I added the color with a `\colorbox, which sets the background color. I did encounter some spacing issues with that part, which really should be addressed, as a change in font or other settings will make the abstract part look really terrible.

\documentclass[a4paper, twocolumn]{article}
\usepackage[table]{xcolor}
\usepackage{lipsum}
\usepackage{mathtools}
\usepackage{tabularx}
\usepackage{booktabs}
\begin{document}
\twocolumn[{
{\huge\bfseries Title of this article}
\medskip
\hrule

\bigskip\medskip

\textbf{First author:}

\bigskip
\hrule
\colorbox{gray!15}{%
    \parbox{\textwidth-.93em}{%
        \vskip1.5ex
        \begin{minipage}[t]{2cm}
            \bfseries Abstract:
        \end{minipage}
        \begin{minipage}[t]{\textwidth-2.5cm}
            \lipsum[2]
        \end{minipage}
        \vskip1.5ex
    }
}
\hrule
\bigskip

}]

\section{Introduction}
\lipsum[2-3]
\newpage
\begin{align*}
\intertext{The same list}
 123&=123\\ 
123+321&=444    
\end{align*}
\end{document}

Answer 2

In this solution based on Tikz, you have a new command \myabstract that takes a single mandatory argument which is the abstract content. The title Abstract is automatic, in the sense that if you change language in babel, it will change by itself, and the indentation of the content will change accordingly. Try commenting out the line about babel to see what I mean.

Of course, it can be changed manually with \renewcommand\abstractname{RandomTitle}

The optional argument of the abstract is the author's name.

Output

Code

\documentclass[a4paper, twocolumn]{article}
\usepackage[margin=2cm]{geometry}
\usepackage{tikz}
\usepackage{calc}  
\usepackage{enumitem}
\usepackage{lipsum,adjustbox}
\usepackage{fancyhdr}

%\usepackage[spanish]{babel} % try Swedish!

\pagestyle{fancy}
\fancyhf{}
\fancyhead[L]{\Huge\bfseries Title of the article}
%\fancyhead[LO,RE]{\slshape\nouppercase{\rightmark}} %these are useless without twoside option
%\fancyfoot[CE,CO]{}
%\fancyfoot[LE,RO]{}
\setlength{\headheight}{30pt}

\newcommand\myabstract[2][First author]{%
\noindent
\twocolumn[{%
\begin{tikzpicture}
    \node[fill=black!5, inner sep=3mm, outer sep=0, minimum width=\textwidth, inner ysep=2mm] (a) {%
    \begin{varwidth}{\textwidth-6.2mm}
    \begin{description}[labelsep=0pt, labelwidth=\widthof{\bfseries \abstractname:~}, leftmargin=!] \item[\abstractname:]#2\end{description}\end{varwidth}};
\draw (a.north west) -- (a.north east);
\draw (a.south west) -- (a.south east);
\node[font=\bfseries, anchor=south west, outer ysep=5mm, outer xsep=0, inner xsep=0] at (a.north west) {#1};
\end{tikzpicture}%
\vspace*{1cm}
}]%
}

\begin{document}

\myabstract{Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed eu convallis urna. Suspendisse potenti. Ut posuere euismod leo, eu posuere arcu vulputate quis. Praesent dictum tempus tortor, elementum gravida nisl eleifend gravida. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Nulla iaculis arcu at risus placerat lobortis. Vestibulum ligula nulla, suscipit congue urna in, congue pellentesque quam. Proin laoreet, orci eget pharetra aliquam, risus felis lobortis justo, in fringilla diam nisi ac enim.}

\section{Introduction}
\lipsum[2-3]
\end{document}