body {
  max-width: 40em;
  margin: 0 auto;
  padding: 5px;
  font-family: Tahoma, sans-serif;
  font-size: 18px;
  line-height: 1.6em;
  color: black;
  background-color: #b4ed9f;  
}
h1, h2, h3 {
  font-family: sans-serif;
  font-weight: normal;
}
img{
width:400px;
height:auto;
}