body {
  background: url("/back.png");
  background-size: cover;
  width: 100%;
  margin: auto;
}

main {
  max-width: 1000px;
  width: 100%;
  margin: auto;
  margin-top: 20px;
}

main img {
  width: 100%;
}

main div {
  font-size: 24px;
  font-weight: 600;
  font-family: 'Noto Sans JP', sans-serif;
  color: #FFF;
  text-align: center;
  background: #2ea42c;
  width: 80%;
  margin: auto;
  padding: 20px 0;
  border-radius: 40px;
  margin-top: 40px;
}

@media screen and (max-width: 700px) {
  body {
    background-size: contain;
  }

  main {
    margin-top: 0;
  }

  main div {
    font-size: 3.8vw;
    width: 95%;
  }
}