\input regression-test.tex
\documentclass{article}
\usepackage{osgstyler}

\DeclareOsgColorPalette{block-traits-test}{
  primary = {model=HTML, value=223344},
  text = {model=HTML, value=111111},
  background = {model=HTML, value=FFFFFF},
  accent = {model=HTML, value=FFD966}
}

\DeclareOsgBlockTrait{rounded}{corner-radius=6pt}
\DeclareOsgBlockTrait{shadow}{shadow=true, shadow-offset=2pt}

\DeclareOsgBlockInstance{mybox}{
  traits={rounded, shadow}, rule-thickness=.4pt, background=accent
}

\NewOsgStyledEnvironment{mybox}{mybox}{none}[1]{#1}

\begin{document}
\UseOsgColorPalette{block-traits-test}
\START
\ExplSyntaxOn
\__osgstyler_block_instance_resolve:n
  { traits={rounded, shadow}, rule-thickness=.4pt, background=accent }
\TYPE{resolved-keys=\tl_use:N\l__osgstyler_block_instance_keys_tl}
\ExplSyntaxOff
\begin{mybox}{Traits}
  \TYPE{mybox-body=shown}
\end{mybox}
\StyleOsgBlockInstance{mybox}{traits={rounded}, rule-thickness=.8pt}
\begin{mybox}{Restyled}
  \TYPE{restyled-body=shown}
\end{mybox}
\TYPE{done}
\END
\end{document}