body {
  margin: 0 auto;
  font-size: 20px;
}

#post-comment {
  margin-top: 20px;
  text-align: center;
}
li {
  list-style: none;
  height: 30px;
  width: 100%;
  padding: 1em;
}

li:nth-child(odd) {
  background-color: lightgrey;
}