style.css

/* Header font */
  @import url('https://fonts.googleapis.com/css2?family=Petrona:ital,wght@0,300;1,300&display=swap');

/* Mono font */
  @import url('https://fonts.googleapis.com/css2?family=Source+Code+Pro:ital,wght@0,200..900;1,200..900&display=swap');

/*Body font */
  @import url('https://fonts.googleapis.com/css2?family=Red+Hat+Text:ital,wght@0,300..700;1,300..700&display=swap');

/*Nav bar font */
  @import url('https://fonts.googleapis.com/css2?family=Red+Hat+Text:ital,wght@0,300..700;1,300..700&display=swap');

/*css for Google Scholar Icon */
  @import url('https://cdn.rawgit.com/jpswalsh/academicons/master/css/academicons.min.css');

/*------------- Body and header text---------------- */

.book.font-family-1 {
  font-family: 'Red Hat Text', sans-serif;
}

h1, h2, h3, h4 {
  font-family: 'Petrona', sans-serif;
  color: rgba(0, 0, 0, 0.8);
}

.book .book-body .page-wrapper .page-inner section.normal h1 {
    font-size: 25px;
}

.book .book-body .page-wrapper .page-inner section.normal h2 {
    font-size: 20px;
}

.title {
  font-family: 'Petrona', sans-serif;
  font-size: 40px;
  color: rgba(0, 0, 0, 0.8);
 }

.code.r {
  font-family: 'Source Code Pro', monospace;
  color: rgba(0, 0, 0, 0.8);
}

.pre {
  font-family: 'Source Code Pro', monospace;
  color: rgba(0, 0, 0, 0.8);
}