Does anybody know how can I remove the black color generated in the background?
\documentclass{beamer}
\usetheme{Hannover}
\usepackage{xcolor}
\usepackage{tikz}
\usepackage{pgfmath}
\usetikzlibrary{decorations.text, arrows.meta,calc,shadows.blur,shadings}
\begin{document}
\begin{frame}
\begin{adjustbox}{max totalsize={.95\textwidth}{.8\textheight},center}
\begin{tikzpicture}[
% Environment Cfg
font=\bf \footnotesize,
% Styles
myarrow/.style={
thick,
-latex,
},
Center/.style ={
circle,
fill=GRIS!10,
text=black,
align=center,
font =\footnotesize\bf,
inner sep=9pt,
},
RO/.style ={
text=black,
color=black,
thick,
fill=RO!90,
blur shadow, %Tikzedt not suport online view
},
RM/.style ={
color=black,
thick,
fill=RM!90,
blur shadow, %Tikzedt not suport online view
},
RC/.style ={
color=black,
thick,
fill=RC!80,
blur shadow, %Tikzedt not suport online view
},
AO/.style ={
text=black,
color=black,
thick,
fill=AO!90,
blur shadow, %Tikzedt not suport online view
},
AM/.style ={
color=black,
thick,
fill=AM!90,
blur shadow, %Tikzedt not suport online view
},
AC/.style ={
color=black,
thick,
fill=AC!90,
blur shadow, %Tikzedt not suport online view
},
VO/.style ={
text=black,
color=black,
thick,
fill=VO!90,
blur shadow, %Tikzedt not suport online view
},
VM/.style ={
color=black,
thick,
fill=VM!70,
blur shadow, %Tikzedt not suport online view
},
VC/.style ={
color=black,
thick,
fill=VC!70,
blur shadow, %Tikzedt not suport online view
},
OO/.style ={
color=GRIS,
thick,
fill=OO!90,
blur shadow, %Tikzedt not suport online view
},
OM/.style ={
color=GRIS,
thick,
fill=OM!90,
blur shadow, %Tikzedt not suport online view
},
OC/.style ={
color=GRIS,
thick,
fill=OC!90,
blur shadow, %Tikzedt not suport online view
},
]
% Drawing the center
\node[Center](SOSA) at (0,0) { HYDROLOGICAL\\ IMPACT UNDER \\ FUTURE CLIMATE };
\coordinate (SOSA-R) at (1.5:1.5); % To make compatible with \arcarrow macro.
% Drawing the Tex Artyle][box-height](radious)(start-angl)(end-angl){|text-styles| Text}cs
%\Arctext[ID][box-s
\arctext[ST][RO][9pt](5.5)(88)(2){|\footnotesize\bf\color{white}| I. STUDY AREA};
\arctext[L][RM][9pt](4.5)(88)(2){|\footnotesize| Location};
\arctext[C][RC][9pt](3.5)(88)(2){|\footnotesize| Clima};
\arctext[IM][VO][9pt](5.5)(178)(92){|\footnotesize\bf\color{white}| II. IMPROVMENT OF DAILY SERIES};
\arctext[IN][VM][9pt](4.5)(178)(92){|\footnotesize| TRMM-TMPA Validation over UCB};
\arctext[TR][VC][9pt](3.5)(178)(92){|\footnotesize| Interpolation techniques};
\arctext[FC][OO][9pt](5.5)(182)(268){|\footnotesize\bf\color{white}| III. FUTURE CLIMA PROJECTION};
\arctext[GC][OM][9pt](4.5)(182)(268){|\footnotesize| GCM Selection};
\arctext[DS][OC][9pt](3.5)(182)(268){|\footnotesize| Downscalling Method};
\arctext[HM][AO][9pt](5.5)(272)(358){|\footnotesize\bf\color{white}| IV. HYDROLOGICAL MODELLING };
\arctext[CAL][AM][9pt](4.5)(272)(358){|\footnotesize|Calibration };
\arctext[VAL][AC][9pt](3.5)(272)(358){|\footnotesize| Validation};
{|\footnotesize\bf\color{white}| THESIS STRUCTURE};
\arcarrow(below TR)(SOSA-R)[45];
\arcarrow(below C)(SOSA-R)[45];
\arcarrow(below DS)(SOSA-R)[315];
\arcarrow(below VAL)(SOSA-R)[315];
\end{tikzpicture}
\end{adjustbox}
\end{frame}
\end{document}
\pagecolor{white}
. I can't test with the given MWE as it does not compile as is.