function resizeText(multiplier) {
  if (document.body.style.fontSize == "") {
    // By first call of this function, the font size must be initialized!
    // 16px = 1.0em
    // 12px = 1.oem *(12px/16px) = 0.75
    document.body.style.fontSize = "0.75em"
    
  }
  document.body.style.fontSize = parseFloat(document.body.style.fontSize) + (multiplier * 0.05) + "em";
}

function resetTextSize() {
    // 16px = 1.0em
    // 12px = 1.oem *(12px/16px) = 0.75
    document.body.style.fontSize = "0.75em";
}