\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[margin=18mm]{geometry}
% The package option establishes the initial gap for every board.
\usepackage[columnsep=3mm,reference-date=2026-07-18]{kanban-board}

\pagestyle{empty}

\begin{document}

\section*{Configuring the gap between columns}

\subsection*{Package default: 3 mm}
\begin{kanban}[columns={Todo,Doing,Done}]
  \kanbantask[prio=high,deadline=01/01/2000]
    {Todo}{Define the interface}
  \kanbantask[author=Alice,
    due=07/18/2026]
    {Doing}{Write the implementation}
  \kanbantask[completed,deadline=12/31/2099]{Done}{Run the tests}
\end{kanban}

\bigskip

% \kbset changes the default for every board that follows it.
\kbset{columnsep=1mm}
\subsection*{Document default changed to 1 mm}
\begin{kanban}[columns={Todo,Doing,Done}]
  \kanbantask[prio=high,deadline=01/01/2000]
    {Todo}{Define the interface}
  \kanbantask[author=Alice,
    due=07/18/2026]
    {Doing}{Write the implementation}
  \kanbantask[completed,deadline=12/31/2099]{Done}{Run the tests}
\end{kanban}

\bigskip

% An environment option overrides the current default for this board only.
\subsection*{Local override: 4 mm}
\begin{kanban}[columns={Todo,Doing,Done},columnsep=4mm]
  \kanbantask[prio=high,deadline=01/01/2000]
    {Todo}{Define the interface}
  \kanbantask[author=Alice,
    due=07/18/2026]
    {Doing}{Write the implementation}
  \kanbantask[completed,deadline=12/31/2099]{Done}{Run the tests}
\end{kanban}

\end{document}