The backgroundcolor
is for the Default
background style:
\documentclass{tikzposter}
\usetheme{Desert}
%% OTHER COLOUR ADJUSTMENTS:
\colorlet{blockbodybgcolor}{white}
\colorlet{backgroundcolor}{gray}
\usebackgroundstyle{Default}
\begin{document}
\maketitle % See Section 4.1
\block{BlocktitleA}{Blocktext} % See Section 4.2
\begin{columns} % See Section 4.4
\column{0.3} % See Section 4.4
\block{BlocktitleB}{Blocktext}
\column{0.7}
\block{BlocktitleC}{Blocktext}
\note{Notetext} % See Section 4.3
\end{columns}
\end{document}
As an alternative: create new background style
\documentclass{tikzposter}
\usetheme{Desert}
%% OTHER COLOUR ADJUSTMENTS:
\colorlet{blockbodybgcolor}{white}
\colorlet{backgroundcolor}{gray}
\definebackgroundstyle{mystyle}{
\draw[line width=0pt, bottom color=backgroundcolor, top
color=backgroundcolor!60!white] (bottomleft) rectangle (topright);
\draw[draw=none, line width=0pt, bottom color=titlebgcolor, top
color=framecolor] (bottomleft) rectangle ($(bottomleft)+(\textwidth,3)$);
}
\usebackgroundstyle{mystyle}
\begin{document}
\maketitle % See Section 4.1
\block{BlocktitleA}{Blocktext} % See Section 4.2
\begin{columns} % See Section 4.4
\column{0.3} % See Section 4.4
\block{BlocktitleB}{Blocktext}
\column{0.7}
\block{BlocktitleC}{Blocktext}
\note{Notetext} % See Section 4.3
\end{columns}
\end{document}