<div class="container">
  <!-- Sliderを包むコンテナ要素 -->
  <div id="swiper" class="swiper">
    <!-- スライド要素を包む要素 -->
    <div class="swiper-wrapper">
      <!-- 各スライド -->
      <div class="swiper-slide slide1">
        <p>スライド:1枚目</p>
      </div>
      <div class="swiper-slide slide2">
        <p>スライド:2枚目</p>
      </div>
      <div class="swiper-slide slide3">
        <p>スライド:3枚目</p>
      </div>
    </div>
    <div class="swiper-button-prev"></div>
    <div class="swiper-button-next"></div>
  </div>
  <div class="swiper-pagination"></div>
</div>

.container {
  margin-left: auto;
  margin-right: auto;
  max-width: 100%;
  position: relative;
}
.swiper {
  /*スライダーの幅と高さを調整*/
  width: 90%;
  height: 200px;
  margin: 0.5rem auto;
}

.swiper-slide {
  /*スライド要素の幅と高さを調整*/
  width: 100%;
  height: 100%;

  /*テキストの位置調整*/
  display: flex;
  justify-content: center;
  align-items: center;

  /*テキストの色と太さを指定*/
  color: #fff;
  font-weight: bold;
}

/*各スライドの背景色の設定*/
.slide1 {
  background-color: #88acbd;
}

.slide2 {
  background-color: #99cb1f;
}

.slide3 {
  background-color: #e43a47;
}

/* ページネーション */
.swiper-pagination-bullets.swiper-pagination-horizontal,
.swiper-pagination-custom,
.swiper-pagination-fraction {
  bottom: -3rem; //3文字分下に下げる
}

/* ドット */
.swiper-pagination-horizontal.swiper-pagination-bullets
  .swiper-pagination-bullet {
  width: 1.5rem;
  height: 1.5rem;
  margin: 0.4rem;
  background: #88abda;
  color: #fff;
  font-weight: bold;
  cursor: pointer;
  opacity: 1;
}

/*アクティブなときのスタイル*/
.swiper-pagination-horizontal.swiper-pagination-bullets
  .swiper-pagination-bullet.swiper-pagination-bullet-active {
  transform: scale(1.4);
  border-radius: 50%;
  background-image: radial-gradient(
    #88abda 0% 40%,
    #fff 40% 50%,
    #88abda 50% 100%
  );
}

const swiper = new Swiper(".swiper", {
  navigation: {
    nextEl: ".swiper-button-next",
    prevEl: ".swiper-button-prev"
  },
  pagination: {
    el: ".swiper-pagination", //必須の設定：ページネーションのclass指定
    type: "bullets",
    clickable: "clickable"
  }
});