为盒子添加阴影，增加盒子的立体感，可以多层叠加，并且会使阴影更加丝滑

HTML

<ul class="pagination">
  <li class="page-prev">
    <a class="prev" href="#"><svg t="1580195949197" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="4493" width="20" height="20"><path d="M906.78272 588.78976c-0.02048 8.4992-6.88128 15.36-15.38048 15.37024l-443.6992-0.01024 75.70432 191.68256c2.51904 6.42048 0.48128 13.76256-5.03808 17.90976-5.51936 4.16768-13.13792 4.1472-18.61632-0.09216l-376.5248-289.47456c-3.77856-2.89792-6.00064-7.41376-6.00064-12.16512 0-4.78208 2.22208-9.27744 6.00064-12.1856l376.5248-289.47456c2.7648-2.11968 6.06208-3.19488 9.37984-3.19488 3.23584 0 6.5024 1.03424 9.23648 3.10272 5.51936 4.1472 7.5776 11.48928 5.03808 17.90976L447.68256 419.84l443.71968-0.01024c8.4992 0.01024 15.36 6.88128 15.36 15.36L906.78272 588.78976z" p-id="4494" fill="#777777"></path></svg></a>
  </li>
  <li class="page-number active"><a href="#">1</a></li>
  <li class="page-number"><a href="#">2</a></li>
  <li class="page-number"><a href="#">3</a></li>
  <li class="page-number"><a href="#">4</a></li>
  <li class="page-number"><a href="#">5</a></li>
  <li class="page-number"><a href="#">6</a></li>
  <li class="page-next">
    <a class="next" href="#"><svg t="1580195920917" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="4995" width="20" height="20"><path d="M906.77248 512c0 4.77184-2.21184 9.2672-5.9904 12.17536l-376.5248 289.4848c-2.7648 2.11968-6.06208 3.18464-9.3696 3.18464-3.25632 0-6.5024-1.03424-9.24672-3.09248-5.50912-4.15744-7.5776-11.48928-5.03808-17.90976l75.71456-191.67232L132.58752 604.17024c-8.48896 0-15.36-6.88128-15.36-15.36l0-153.6c0-8.48896 6.87104-15.36 15.36-15.36l443.72992 0-75.71456-191.68256c-2.53952-6.42048-0.47104-13.75232 5.04832-17.90976 5.50912-4.15744 13.12768-4.13696 18.60608 0.09216l376.5248 289.4848C904.56064 502.7328 906.77248 507.22816 906.77248 512z" p-id="4996" fill="#777777"></path></svg></a>
  </li>
</ul>

CSS<scss>

body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: #ECEFFC;
}

.pagination {
  --active-index: 0;
  display: flex;
  padding: 10px 20px;
  background: white;
  border-radius: 50px;
  box-shadow:
  0 0.3px 0.6px rgba(0, 0, 0, 0.056),
  0 0.7px 1.3px rgba(0, 0, 0, 0.081),
  0 1.3px 2.5px rgba(0, 0, 0, 0.1),
  0 2.2px 4.5px rgba(0, 0, 0, 0.119),
  0 4.2px 8.4px rgba(0, 0, 0, 0.144),
  0 10px 20px rgba(0, 0, 0, 0.2)
;
  list-style-type: none;

  li {
    margin: 0 5px;

    &.page-number {
      width: 50px;
      height: 50px;
      line-height: 50px;
      text-align: center;

      &:hover a {
        color: white;
        background: #777;
      }

      &.active a {
        color: white;
        background: #333;
      }
    }

    &.page-prev,
    &.page-next {
      font-weight: 700;
    }

    &.page-prev {
      margin-right: 20px;
    }

    &.page-next {
      margin-left: 20px;
    }

    a {
      display: block;
      line-height: 50px;
      font-size: 20px;
      font-weight: 600;
      text-decoration: none;
      color: #777;
      border-radius: 50%;
      transition: 0.3s;

      &.prev:hover path,
      &.next:hover path {
        fill: darken(#777, 50%);
      }
    }
  }
}

JS<TypeScript>

let prevLink = document.querySelector(".prev");
let nextLink = document.querySelector(".next");
let pagination = document.querySelector(".pagination");
let pageNumberLinks = document.querySelectorAll(".page-number a");
let maxPageIndex = pageNumberLinks.length - 1;
pageNumberLinks.forEach((pageNumberLink, activeIndex) => {
  pageNumberLink.addEventListener("click", () => {
    pageNumberLinks.forEach(pageNumberLink =>
      pageNumberLink.parentElement.classList.remove("active")
    );
    pageNumberLink.parentElement.classList.add("active");
    (pagination as HTMLElement).style.setProperty(
      "--active-index",
      `${activeIndex}`
    );
  });
});
prevLink.addEventListener("click", () => {
  pageNumberLinks.forEach(pageNumberLink =>
    pageNumberLink.parentElement.classList.remove("active")
  );
  let activeIndex = Number(
    (pagination as HTMLElement).style.getPropertyValue("--active-index")
  );
  activeIndex = activeIndex > 0 ? activeIndex - 1 : 0;
  pageNumberLinks[activeIndex].parentElement.classList.add("active");
  (pagination as HTMLElement).style.setProperty(
    "--active-index",
    `${activeIndex}`
  );
});
nextLink.addEventListener("click", () => {
  pageNumberLinks.forEach(pageNumberLink =>
    pageNumberLink.parentElement.classList.remove("active")
  );
  let activeIndex = Number(
    (pagination as HTMLElement).style.getPropertyValue("--active-index")
  );
  activeIndex = activeIndex < maxPageIndex ? activeIndex + 1 : maxPageIndex;
  pageNumberLinks[activeIndex].parentElement.classList.add("active");
  (pagination as HTMLElement).style.setProperty(
    "--active-index",
    `${activeIndex}`
  );
});