presentation.css

blockquote {
  background: #f9f9f9;
  border-left: 5px solid #ccc;
  margin: 0.75em 10px;
  padding: 0.5em 0.75em;
}

blockquote {
    text-align: left;
}

footer {
  text-align: right;
}

img.centered {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

table.kable_wrapper {
  width: 80%;
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

.quote {
  width: 50%;
  margin-left: 25%;
  margin-right: 25%;
  background-color: gray;
  padding: 5%;
}

.quote > p:nth-child(2) {
  color: red;
  text-align: right;
}