styles.css

pre {
  font-family: 'Source Code Pro', 'Courier New', monospace;
  font-size: 24px;
  line-height: 24px;
  padding: 10px 0 10px 60px;
  letter-spacing: -1px;
  margin-bottom: 8px;
  width: 106%;
  left: -60px;
  position: relative;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
  /*overflow: hidden;*/
}

/* Whole document: */
body{
  font-family: Helvetica;
  font-size: 16pt;
}

/* Headers */
h1{
  font-size: 28pt;
}
h2{
  font-size: 24pt;
}
h3{
  font-size: 20pt;
}


.emphasized {
   font-size: 1.2em;
}

.small {
   font-size: 0.8em;
}

strong { 
    font-weight: bold;
    color: black;
}

/*
slides > slide {
  padding: 10px 60px;
}
*/
slides > slide > hgroup + article {
    margin-top: 5px;
}

.left_col {
   float:left;
   width:48%;
}
.right_col {
   float:right;
   width:48%;
}

slides>slide.title-slide {
    background-image: url('images/Intro_to_R.png');
    background-size: 100% 100%;
}

.codesmall pre {
    font-size: 16px;
}

.codeexample pre{
  background-color: lightgreen;
}