h1,
h2,
h3,
h4 {
  position: relative;
  margin-top: 1.2em;
  font-weight: bold;
}
h1 {
  margin-bottom: 1.2em;
}
h1::before {
  content: "";
  position: absolute;
  bottom: -1rem;
  left: 0;
  height: 4px;
  width: 60px;
  background: #00000029;
}
h3 {
  font-size: 1.4em;
}
h4 {
  font-size: 1.2em;
}
#main-content .container {
  max-width: 1000px;
}
#references li {
  margin-bottom: 1em;
}