Height of colorbox

Question

I'm trying to "highlight" two parts of a sentence by using a \colorbox like so:

\colorbox{red}{This is} \colorbox{blue}{a great sentence.}

The problem is that in the second part the height colorbox is a bit bigger, because it contains a g which extends below the baseline. As a result, the two colorboxes do not align at the bottom which looks suboptimal.

How would I make the two boxes line up?

Answer 1

You can use a \strut

{\colorbox{red}{\strut This is} \colorbox{blue}{\strut a great sentence.}}

LaTeX/TEX define \strut to be an invisible box of width zero that extends just enough above and below the baseline.

Answer 2

Let's compare and decide which one do you prefer :)

---

\documentclass{article}

\usepackage[paperwidth=10cm,paperheight=10cm]{geometry}
\usepackage{graphicx}
\usepackage{xcolor}


\usepackage{calc}

%Define a reference depth. 
%You can choose either relative or absolute.
%--------------------------
\newlength{\DepthReference}
\settodepth{\DepthReference}{g}%relative to a depth of a letter.
%\setlength{\DepthReference}{6pt}%absolute value.

%Define a reference Height. 
%You can choose either relative or absolute.
%--------------------------
\newlength{\HeightReference}
\settoheight{\HeightReference}{T}
%\setlength{\HeightReference}{6pt}


%--------------------------
\newlength{\Width}%

\newcommand{\MyColorBox}[2][red]%
{%
    \settowidth{\Width}{#2}%
    %\setlength{\fboxsep}{0pt}%
    \colorbox{#1}%
    {%      
        \raisebox{-\DepthReference}%
        {%
                \parbox[b][\HeightReference+\DepthReference][c]{\Width}{\centering#2}%
        }%
    }%
}

\setlength{\fboxsep}{1pt}
\begin{document}

\noindent @Thomas \hrulefill\colorbox{red}{This is} \colorbox{blue}{a great sentence.}\hrulefill

\vspace{5mm}

\noindent @Yiannis \hrulefill{\colorbox{red}{\strut This is} \colorbox{blue}{\strut a great sentence.}}\hrulefill

\vspace{5mm}

\noindent @xport \hrulefill\MyColorBox{This is} \MyColorBox[blue]{a great sentence.}\hrulefill


\end{document}

---

EDIT 1:

My idea above can be explained as follows:

1. I choose the tallest letter as a reference for common height.
2. I choose the deepest letter as a reference for common depth.
3. Then a make a parbox with constant height based on the sum of height and depth mentioned in step 1 and 2.
4. Move the parbox down as far as the depth mentioned in step 2.

Answer 3

\documentclass[a5paper,12pt]{article}

\usepackage{soul,xcolor}
\sethlcolor{red}
\begin{document}

\hl{This is} \hl{\strut a great sentence.}

\end{document}