% arara: lualatex
% arara: lualatex
% arara: ghostscript: { resolution: 250 , device: png16m}
% arara: cleanx: { extensions: [ aux , toc , log , bbl , bcf , blg , out , run.xml, gz, listing ] }
\documentclass[a4paper]{article}
\usepackage[margin=20mm, paperheight=33cm]{geometry}
\usepackage{tikz}
% stepcolors
\foreach \N/\n in {0/black, 1/brown, 2/red!70,
3/orange, 4/yellow!80!orange, 5/green!70!black,
6/blue!50, 7/violet!60, 8/gray}{
\xglobal\colorlet{stepcolor\N}{\n}
}
\makeatletter
\def\IsColorDefined#1{\@ifundefined{\string\color@#1}{black}{#1}}