Bold horizontal and vertical lines in tables

Question

I want to be able to make certain horizontal lines and certain vertical lines bold in my table but not all.

\begin{table}[h] 
\begin{center} 
\begin{tabular}{|c|c|c|c|c|c|c|} 
\hline
$x$&100&10 000&$1$x$10^5$&$1$x$10^6$&$1$x$10^7$&$1$x$10^9$\\
\hline
$f(x)$&0,1&0,0001&$1$x$10^-5$&$1$x$10^-6$&$1$x$10^-7$&$1$x$10^-9$\\
\hline
\end{tabular}
\end{center}
\end{table}

I am looking for a box border, center line not bold. First 3 vertical lines and last to be bold.

Thanks for the help

Answer 1

You can also have the border thicker if you supress the outer vlines and hlines, and replace them with an \fbox with no fboxsep. I added the vertical alignment of numbers in scientific notation thanks to the numprint package and its n/N column types, some more vertical spacing in cells with the cellspace package — and some colors…

\documentclass[12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}

\usepackage{array}
\usepackage{cellspace}
\setlength\cellspacetoplimit{8pt}
\setlength\cellspacebottomlimit{8pt}
\usepackage[autolanguage, np]{numprint}
\usepackage[svgnames, x11names, tables]{xcolor}

\begin{document}

\begin{table}[h]
\centering\setlength\fboxsep{0pt}\setlength\fboxrule{1.5pt}
\fcolorbox{LightSteelBlue3}{White}%
{\begin{tabular}{r!{\color{Salmon1}\vrule width1.2 pt}Sc|c|*{3}{n{1}{1}|}n{1}{1}}%{r@{\hskip\tabcolsep\vrule width1 pt\hskip\tabcolsep}Sl|c|c|c|c|c}%
$x$ & 100 & 10 000 &  \np{1e5} &  \np{1e6} &  \np{1e7} & \np{1e9}\\
\hline
$f(x)$ & 0,1  & 0,0001 &  \np{1e-5} & \np{1e-6} & \np{1e-7} & \np{1e-9}
\end{tabular}}
\end{table}

\end{document}