html {
  font-family: 'PT Serif', serif;
  font-size: 18px;
  line-height: 1.6;
  /* create a visual baseline grid repat every 29px*/
  /*background-image: linear-gradient(to bottom, transparent 0px, transparent 28px, red 28px, red 29px);
  background-size: 100% 29px;*/
}

body {
  margin: 0 auto;
  max-width: 32em;
  padding: 0 29px;
}

h1, h2, h3 {
  margin: 29px 0; /* 18px * 1.6 =  28.8px */
}

p, ul, ol, blockquote {
  margin: 22px 0; /* 18px * 1.6 * 0.75 = 21.6px */
}

ul, ol {
  padding: 0;
  margin-left: 32.4px; /* 14.4px + 18px = 32.4px Half baseline + font size */
}

li + li {
  margin-top: 7px; /* 0.25 baseline */
}

h1 {
  font-size: 2.369em; /* 42.642px */
  line-height: 58px; /* 18px * 1.6 * 2 = 57.6px*/
}

h2 {
  font-size: 1.777em; /* 31.986px */
  line-height: 43px; /* 18px * 1.6 * 1.5 = 43.2px*/
}

h3 {
  font-size: 1.333em; /* 23.994px */
  line-height: 29px; /* 18px * 1.6 = 28.8px */
}
blockquote {
  border-left: 7px solid #ccc; /* 0.25 baseline = 7.2px */
  padding-left: 25.4px; /* 14.4px + 18px - 7px = 32.4px : Half baseline + font size - border-left width */
  color: #888;
}

.inset {
  font-size: 0.64em; /* 11.52px */
  float: left;
  max-width: 16em;
  margin: 6px 15px 0 0;
  line-height: 21.6px; /* 18px * 1.6 * 0.75 =  21.6px*/
}

.button {
  text-align: center;
  background-color: #ccc;
  max-width: 120px;
  line-height: 29px; /* 18px * 1.6 = 28.8px*/
  padding: 15px; /* 0.5 baseline */
}

.row + .row {
  margin-top: 15px; /* 0.5 baseline */
}

.shape {
  width: 100px;
  height: 100px;
  background-color: #333;
  display: inline-block;
  border: 1px;
  border-radius: 100%;
}

.shape + .shape {
  margin-left: 15px; /* 0.5 baseline */
}