<h1>Beetles</h1>
<h2>External morphology</h2>
<h3>Head</h3>
<h4>Mouthparts</h4>
<h3>Thorax</h3>
<h4>Prothorax</h4>
<h4>Pterothorax</h4>

h1,
h2,
h3,
h4 {
  margin: 0.1rem 0;
}

h1 {
  font-size: 2rem;
}

h2 {
  font-size: 1.5rem;
  padding-left: 20px;
}

h3 {
  font-size: 1.2rem;
  padding-left: 40px;
}

h4 {
  font-size: 1rem;
  font-style: italic;
  padding-left: 60px;
}