How do I enter a tiny vertical space above the first row in a table?

Question

Consider the following MRE where you would notice that it's difficult for the average reader to see the bars above Q and k.

\documentclass[11pt]{article}
\begin{document}
\begin{tabular}{|c|c|}
\hline
    cell 1 & cell2 \\ \hline
    $\bar{k}$ & $\bar{Q}$ \\ \hline
\end{tabular}
\end{document}

How do I fix this issue? I don't really mind whether you insert a vertical space above the letters or use a more clever way -- I'm simply looking for a solution to this issue without having to write a lot of code (so that I can remember it and reproduce later when needed).

Answer 1

You could use the tabularray package. It has a less crowed spacing by default and thus avoids the problem:

\documentclass[11pt]{article}

\usepackage{tabularray}

\begin{document}

\begin{tblr}{|c|c|}
\hline
    cell 1 & cell2 \\ \hline
    $\bar{k}$ & $\bar{Q}$ \\ \hline
\end{tblr}

\end{document}

Answer 2

I can think of two main solution methods. The first treats the symptom (by inserting a suitable typographic strut), while the second fixes the underlying problem (caused by non-existent vertical spacing adjustments around \hline directives). The second solution also provides a more open "look" by getting rid of the unneeded vertical lines.

\documentclass[11pt]{article}
\usepackage{booktabs} % for \toprule, \midrule, and \bottomrule macros

\begin{document}

\begin{tabular}[t]{|c|c|}
    \hline
    header 1 & header 2 \\ \hline
    $\bar{k}$ & $\bar{Q}$ \\ 
    \hline
\end{tabular}
\quad 
% fix 1: treat the symptom
\begin{tabular}[t]{|c|c|}
    \hline
    header 1 & header 2 \\
    \hline
    $\bar{k}$ & $\bar{Q}^{\strut}$ \\ \hline
\end{tabular}
\quad 
% fix 2: treat the underlying problem
\begin{tabular}[t]{@{} cc @{}}
    \toprule
    header 1 & header 2 \\ 
    \midrule
    $\bar{k}$ & $\bar{Q}$ \\ 
    \bottomrule
\end{tabular}

\end{document}