style.css

/* Tadaa modifications */

.book .book-body .page-wrapper .page-inner section.normal small {
  font-size: smaller;
}

.toc-banner {
  padding: 5px;
}

.toc-banner img {
  max-width: 100%;
}

.toc-headline {
  text-align: center;
  font-size: 18px;
  padding-top: 0;
}
.book .book-body .page-wrapper .page-inner section.normal .subtitle {
  font-size: 60%;
  color: #a8a8a8;
}

#header {
  text-align: center;
  border-top-style: solid;
  border-bottom-style: solid;
  border-color: black;
  border-width: 1px;
}

.title {
  font-variant: small-caps;
}

.book .book-body .page-wrapper .page-inner section.normal p > sup {
  vertical-align: super;
  font-size: 70%;
}

.book .book-body .page-wrapper .page-inner section.normal h1 {
  font-variant: small-caps;
}

/* No "not-allowed"-cursor on toc hearders */
.book .book-summary ul.summary li span {
  cursor: unset !important;
}

/* Original CSS by Yihui below */

.rmdcaution, .rmdimportant, .rmdnote, .rmdtip, .rmdwarning {
  padding: 1em 1em 1em 4em;
  margin-bottom: 10px;
  background: #f5f5f5 5px center/3em no-repeat;
}
.rmdcaution {
  background-image: url("../images/caution.png");
}
.rmdimportant {
  background-image: url("../images/important.png");
}
.rmdnote {
  background-image: url("../images/note.png");
}
.rmdtip {
  background-image: url("../images/tip.png");
}
.rmdwarning {
  background-image: url("../images/warning.png");
}
p.caption {
  color: #777;
  margin-top: 10px;
}
p code {
  white-space: inherit;
}
pre {
  word-break: normal;
  word-wrap: normal;
}
pre code {
  white-space: inherit;
}
p.flushright {
  text-align: right;
}
blockquote > p:last-child {
  text-align: right;
}
blockquote > p:first-child {
  text-align: inherit;
}
.header-section-number {
  padding-right: .2em;
  font-weight: 500;
}
.level1 .header-section-number {
  display: inline-block;
  border-bottom: 3px solid;
}
.level1 h1 {
  border-bottom: 1px solid;
}
h1, h2, h3, h4, h5, h6 {
  font-weight: normal;
}
h1.title {
  font-weight: 700;
}
.book .book-body .page-wrapper .page-inner section.normal strong {
  font-weight: 500;
}