body {
	max-width: 80ch;
	padding: 3em 1em;
	margin: auto;
	line-height: 1.6;
	font-size: 1.25em;
	font-family: Helvetica;
  }
  
  .d {
	font-size: medium;
	color: grey;
  }
  
  img {
	max-width: 100%;
	height: auto;
  }
  
  pre {
	overflow: auto;
  }