\geometry{
  a4paper,
  paperwidth=21cm,
  paperheight=35cm,
  headheight=2.5cm,
  total=17cm,
  left=3cm,
  right=3cm,
  top=3cm,
  headsep=0.5cm,
  hoffset=-1.5cm,
  bottom=3cm,
}

\setlength{\parindent}{0cm}

