body {
  margin: 0;
  font-family: Arial, sans-serif;
}

.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: #f1f1f1;
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 100;
  padding: 10px;
}

.header  .logo {
  font-size: 24px;
}
.logo {
  font-size: 24px;
  height: 50px;
}

.image {
  padding: 20px 20px;
  width: 800px;
  display: block;
  max-width: 100%;
  height: auto;
  }
  /* PC用のスタイル */
  @media (min-width: 768px) {
    .banner {
      background-color: black;
      padding: 200px 0;
      text-align: center;
      padding-bottom: 150px;
      font-size: 120px;
      font-weight: bold;
      color: white;
      width: 100%;
        }
    .title {
      font-size: 40px;
      font-weight: bold;
    }
    .image {
      content: url('image2.png');
    }
    .image2 {
      width: 200px;
      content: url('GooglePlay.png');
    }      
    .image3 {
      width: 350px;
      content: url('appcore.png');
    }
    .content {
      padding: 50px 50px;
      margin: 0 auto;
      width: 800px;
    }
    .explain {
      padding: 10px 50px;
      margin: 0 auto;
      width: 800px;
    }
    .app {
      padding: 10px 50px;
      margin: 0 auto;
      width: 800px;
    }
    .store {
      padding: 50px 50px;
      margin: 0 auto;
      width: 800px;
    }
  }

  /* スマートフォン用のスタイル */
  @media (max-width: 767px) {
    .banner {
      padding-bottom: 90px;
      font-size: 50px;
      background-color: black;
      padding-top: 150px;
      text-align: center;
      font-weight: bold;
      color: white;
      width: 100%;
    }
    .title {
      font-size: 25px;
      font-weight: bold;
    }
    .image {
      content: url('image3.png');
    }      
    .image2 {
      width: 200px;
      content: url('GooglePlay.png');
    }      

    .image3 {
      width: 300px;
      content: url('appcore.png');
    }
    .content {
      padding: 50px 50px;
      margin: 0 auto;
      width: 80%;
    }
    .explain {
      padding: 10px 50px;
      margin: 0 auto;
      width: 80%;
    }
    .app {
      padding: 10px 50px;
      margin: 0 auto;
      width: 80%;
    }
    .store {
      padding: 50px 50px;
      margin: 0 auto;
      width: 80%;
    }

  }

.image2 {
  padding: 10px 20px;
  display: block;
  max-width: 100%;
  height: auto;
  }
  
.header .menu {
  display: flex;
  align-items: center;
}

.header .menu a {
  margin-right: 10px;
  text-decoration: none;
  color: black;
}

.header .menu select {
  border: none;
  background-color: #f1f1f1;
  margin-right: 15px;
}

  


.section {
  margin-bottom: 30px;
  margin-left: 10px;
}

.section h2 {
  font-size: 24px;
  margin-bottom: 10px;
}

.footer {
  background-color: black;
  color: white;
  text-align: center;
  padding: 20px 0;
}

.footer a {
  color: white;
  text-decoration: none;
  margin: 0 10px;
}