* {
  box-sizing: border-box;
}
body {
  background: gainsboro;
  color: black;
  
  max-width: 48em;
  margin: 1em auto;
  padding: 24px;
  border-left: thin solid black;
  
  font-family: system-ui, sans-serif;
  }
  
/* a */
a {
  color: black;
  text-decoration: none;
  }
  
/* header */
header a {
  font-size: 32px;
  font-weight: 600;
  
  margin-bottom: .25em;
  
  transition: color .2s;
  }
header a:hover {
  color: #ccffcc;
}
/* nav */
nav a {
  font-weight: 500;
  
  margin-right: .75em;
  
  transition: color .2s;
  }
nav a:hover {
  color: #ccffcc;
}

/* hr */
hr {
  border-top: thin solid black;
  }