\usepackage{tikz}
\usepackage{pgf}
\usetikzlibrary{positioning}
\usetikzlibrary{calc}
\usetikzlibrary{automata}
\usetikzlibrary{arrows}
\usetikzlibrary{backgrounds}
\usetikzlibrary{fit}
\usetikzlibrary{shadows}
\usepackage{tikz-qtree}
\usepackage{graphicx} 
\usepackage{pgfplots}



\pgfplotsset{compat=1.15}

\newenvironment{bubble}[1][]{%
\addtolength{\leftmargini}{4mm}%
\begin{tikzpicture}[baseline=(current bounding box.north)]%
\draw (0,0) node[drop shadow,inner sep=2mm,fill=cream,ultra thick,draw=red,rounded corners=2mm]% 
\bgroup\begin{minipage}{#1}\raggedright{}}
{\end{minipage}\egroup;%
\end{tikzpicture}\bigskip}