cal.pub0.org/apps/docs/pages/style.css

@font-face {
  font-family: 'Cal Sans';
  src: url("https://cal.com/cal.ttf");
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: 'Cal Sans';
  font-weight: normal;
  letter-spacing: normal;
}