\ProvidesPackage{ptbposter-add}[2019/05/10 v0.1a ptbposter/tcolorbox (RN)]

\newcommand*\PTB@showframe{false}
\DeclareOption{showframe}{%
  \def\PTB@showframe{true}
}%
\DeclareOption*{\OptionNotUsed}
\ProcessOptions\relax

\RequirePackage[most]{tcolorbox}
\tcbuselibrary{poster}
\usetikzlibrary{shadings}

\colorlet{backgroundTop}{Goldenrod2!10}
\colorlet{backgroundBottom}{Goldenrod2!70}
\colorlet{boxBackground}{white}

\tcbposterset{%
  poster={%
    columns= 3,
    rows   = 5,
    spacing=\PTB@texthsep,
    showframe=\PTB@showframe,
  },    
  coverage={%
    height=\textheight,
    width=\textwidth,
    interior style={opacity=0},
    top=0pt,bottom=0pt,left=0pt,right=0pt
  },%
  boxes = {
    enhanced standard jigsaw,sharp corners=downhill,
    arc=0.012\PTB@scale@base,
    boxrule=\PTB@framethickness,
    boxsep=0pt,
    top=1ex,bottom=1ex,left=1ex,right=1ex,
    toptitle=.6ex,bottomtitle=.6ex,lefttitle=1ex,righttitle=1ex,
    colback=boxBackground,
    %opacityback=0.75,% ????
    colframe=PTBcolor,
    coltitle=white,
    fonttitle      =\sffamily\bfseries,
    title style={
      PTBcolor
    },
    valign=top% center
  }
}%

\renewcommand*\backgroundContent{%
  \begin{tikzpicture}%
    \shade[top color=backgroundTop, bottom color=backgroundBottom,%
      shading angle=\ifPTB@landscape 35.26\else 54.74\fi](0,0)%
      rectangle(\PTB@framewidth,\PTB@frameheight);%
  \end{tikzpicture}%  
}

\AtBeginDocument{%
  \begin{tcbposter}%
}
\AtEndDocument{%
  \end{tcbposter}%
}

\endinput