usepackage{xcolor}
usepackage[framemethod=tikz]{mdframed}
usetikzlibrary{shadows,shadings}
usepackage{calc}
usepackage{tikz}
usetikzlibrary{shapes,snakes}

newcounter{demo_counter}

renewcommandthetheorem{Demonstration ~arabic{demo_counter}}


makeatletter
mdf@dolist{mdf@do@stringoption}{%
{theoremtitle=={}}%
}
renewrobustcmdmdfcreateextratikz{%
  node[anchor=west,rounded corners,draw=orange,thick,fill=blue!20,xshift=2cm,minimum height=.7cm,minimum width=2cm] at (P-|O)
      {~mdf@frametitlefont{thetheorem}%
          ifdefempty{mdf@theoremtitle}%
          {~}%
          {:~mdf@theoremtitle~}%
      };
}
makeatother

mdfdefinestyle{theoremstyle}{%
outerlinewidth=1pt,
innerlinewidth=3pt,
roundcorner=5pt,
linecolor=orange,
splittopskip=1cm,         % THIS IS THE REQUIRED OPTION FOR SPACE ABOVE THE SPLIT ON THE SECOND PAGE
splitbottomskip=1cm,      % THIS IS THE REQUIRED OPTION FOR SPACE BELOW THE SPLIT ON THE FIRST PAGE
tikzsetting={fill=blue!5},
innertopmargin=1.2baselineskip,
skipabove={dimexpr0.5baselineskip+topskiprelax},
needspace=3baselineskip,
frametitlefont=sffamilybfseries,
settings={globalstepcounter{demo_counter}},
}

newenvironment{demo}[1][]
{begin{mdframed}[style=theoremstyle,theoremtitle={#1}]
relax}{
end{mdframed}
}

newcounter{remark_counter}
renewcommandtheremark{Remark ~arabic{remark_counter}}
renewrobustcmdmdfcreateextratikz{%
  node[anchor=west,rounded corners,draw=green,thick,fill=blue!20,xshift=2cm,minimum height=.7cm,minimum width=2cm] at (P-|O)
      {~mdf@frametitlefont{theremark}%
          ifdefempty{mdf@remarktitle}%
          {~}%
          {:~mdf@remarktitle~}%
      };
}


mdfdefinestyle{remarkstyle}{%
outerlinewidth=1pt,
innerlinewidth=3pt,
roundcorner=5pt,
linecolor=green,
splittopskip=1cm,
splitbottomskip=1cm,
tikzsetting={fill=blue!5},
innertopmargin=1.2baselineskip,
skipabove={dimexpr0.5baselineskip+topskiprelax},
needspace=3baselineskip,
frametitlefont=sffamilybfseries,
settings={globalstepcounter{remark_counter}},
}

newenvironment{remark}[1][]
{begin{mdframed}[style=remarkstyle,remarktitle={#1}]
relax}{
end{mdframed}
}