main {
  padding: 15px; /* optional outer breathing room */
}

main > section {
  height: 300px;
  padding: 0 40px;              /* left & right padding */
  border: 1px solid #ccc;
  border-radius: 5px;
  background-color: transparent;

  /* spacing between sections */
  margin-bottom: 15px;
}

/* Remove space after last section */
main > section:last-child {
  margin-bottom: 0;
}