.preface_title_1 {
  padding-top: 10mm;
  padding-bottom: 3mm;
  font-size: 6mm;
  font-weight: bold;
  text-align: center;
}
.preface_title_2 {
  padding-bottom: 10mm;
  font-size: 5mm;
  font-weight: bold;
  text-align: center;
}
.preface_title_3 {
  margin-top: 12mm;
  font-size: 4mm;
  line-height: 10mm;
}
.preface_title_4 {
  font-size: 3mm;
  line-height: 8mm;
}
.preface_content {
  font-size: 3mm;
  line-height: 8mm;
  text-indent: 2em;
}
.preface_content_line {
  font-size: 4mm;
  line-height: 8mm;
  border-bottom: 0.3mm dashed #333;
}