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CSS

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HTML 

              
                <nav class="navtab">
  <ul>
    <li class="navtab-item active">
      <svg t="1580196202692" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="781" width="36" height="36"><path d="M555.541333 117.994667l312.874667 224.565333A117.333333 117.333333 0 0 1 917.333333 437.866667V800c0 64.8-52.533333 117.333333-117.333333 117.333333H640V746.666667c0-70.688-57.312-128-128-128s-128 57.312-128 128v170.666666H224c-64.8 0-117.333333-52.533333-117.333333-117.333333V437.877333a117.333333 117.333333 0 0 1 48.917333-95.317333l312.874667-224.565333a74.666667 74.666667 0 0 1 87.082666 0z" p-id="782" fill="currentColor"></path></svg>
      <span>Home</span>
    </li>
    <li class="navtab-item">
      <svg t="1580196351612" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="1159" width="36" height="36"><path d="M512 85.333333c235.637333 0 426.666667 191.029333 426.666667 426.666667S747.637333 938.666667 512 938.666667 85.333333 747.637333 85.333333 512 276.362667 85.333333 512 85.333333z m149.162667 222.901334L444.16 386.357333a96 96 0 0 0-57.802667 57.813334l-78.122666 216.992a42.666667 42.666667 0 0 0 54.602666 54.602666l217.002667-78.122666a96 96 0 0 0 57.802667-57.813334l78.122666-216.992a42.666667 42.666667 0 0 0-54.602666-54.602666zM512 565.333333a53.333333 53.333333 0 1 0 0-106.666666 53.333333 53.333333 0 0 0 0 106.666666z" p-id="1160" fill="currentColor"></path></svg>
      <span>Explore</span>
    </li>
    <li class="navtab-item">
      <svg t="1580196428669" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="2609" width="30" height="30"><path d="M335.008 916.629333c-35.914667 22.314667-82.88 10.773333-104.693333-25.557333a77.333333 77.333333 0 0 1-8.96-57.429333l46.485333-198.24a13.141333 13.141333 0 0 0-4.021333-12.864l-152.16-132.586667c-31.605333-27.52-35.253333-75.648-8.234667-107.733333a75.68 75.68 0 0 1 51.733333-26.752L354.848 339.2c4.352-0.362667 8.245333-3.232 10.026667-7.594667l76.938666-188.170666c16.032-39.2 60.618667-57.92 99.52-41.461334a76.309333 76.309333 0 0 1 40.832 41.461334l76.938667 188.16c1.781333 4.373333 5.674667 7.253333 10.026667 7.605333l199.712 16.277333c41.877333 3.413333 72.885333 40.458667 69.568 82.517334a76.938667 76.938667 0 0 1-26.08 51.978666l-152.16 132.586667c-3.541333 3.082667-5.141333 8.074667-4.021334 12.853333l46.485334 198.24c9.621333 41.013333-15.36 82.336-56.138667 92.224a75.285333 75.285333 0 0 1-57.525333-9.237333l-170.976-106.24a11.296 11.296 0 0 0-12.010667 0l-170.986667 106.24z" p-id="2610" fill="currentColor"></path></svg>
      <span>Collection</span>
    </li>
    <li class="navtab-item">
      <svg t="1580196480651" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="2891" width="30" height="30"><path d="M512 85.333333c235.637333 0 426.666667 191.029333 426.666667 426.666667S747.637333 938.666667 512 938.666667 85.333333 747.637333 85.333333 512 276.362667 85.333333 512 85.333333z m0 586.666667a32 32 0 1 0 0 64 32 32 0 0 0 0-64z m-2.517333-373.333333c-48.416 0-92.746667 24.16-118.613334 63.413333a137.088 137.088 0 0 0-15.978666 33.237333 32 32 0 0 0 60.906666 19.690667c2.016-6.24 4.885333-12.202667 8.522667-17.717333C458.4 375.914667 482.709333 362.666667 509.482667 362.666667 552.277333 362.666667 586.666667 396.266667 586.666667 437.333333s-34.4 74.666667-77.194667 74.666667a32 32 0 0 0-32 32v64a32 32 0 0 0 64 0v-35.584C603.946667 558.197333 650.666667 503.232 650.666667 437.333333c0-76.757333-63.381333-138.666667-141.194667-138.666666z" p-id="2892" fill="currentColor"></path></svg>
      <span>Help</span>
    </li>
  </ul>
</nav>
!

CSS 

              
                @import url(https://fonts.googleapis.com/css?family=Lato);

@mixin center {
  display: flex;
  justify-content: center;
  align-items: center;
}

body {
  @include center;
  height: 100vh;
  font-family: Lato, sans-serif;
  background: #ECEFFC;
}

.navtab {
  --navtab-width: 600px;
  --navtab-item-width: calc(var(--navtab-width) / 4 - 20px);
  --navtab-overlay-width: calc(var(--navtab-item-width) + 80px);
  --active-index: 0;

  position: relative;
  width: var(--navtab-width);
  height: 150px;
  background: white;
  border: 1em solid white;
  // https://9elements.github.io/fancy-border-radius/full-control.html#15.5.15.15-50.95.50.85-150.600
  border-radius: 5% 5% 15% 15% / 15% 15% 50% 50%;
  overflow: hidden;

  ul {
    @include center;
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
    list-style-type: none;

    .navtab-item {
      @include center;
      z-index: 2;
      flex-direction: column;
      width: var(--navtab-item-width);
      height: 100%;
      color: #0288d1;
      cursor: pointer;
      transition: 0.5s ease;

      svg {
        transition: 0.5s ease;
      }

      span {
        font-size: 20px;
        user-select: none;
        opacity: 0;
        transition: 0.5s ease;
      }

      &.active {
        width: var(--navtab-overlay-width);

        svg {
          transform: translateY(-10px);
        }

        span {
          opacity: 1;
        }
      }
    }
  }

  &::after {
    position: absolute;
    content: "";
    top: 0;
    left: 0;
    height: 100%;
    width: var(--navtab-overlay-width);
    background: #b3e5fc;
    border-radius: 20px;
    transform: translateX(calc(var(--navtab-item-width) * var(--active-index)));
    transition: 0.5s ease;
  }
}
!

JS 

              
                let navtab = document.querySelector("nav.navtab");
let navtabItems = document.querySelectorAll("li.navtab-item");
navtabItems.forEach((navtabItem, activeIndex) =>
  navtabItem.addEventListener("click", () => {
    navtabItems.forEach(navtabItem => navtabItem.classList.remove("active"));
    navtabItem.classList.add("active");
    (navtab as HTMLElement).style.setProperty(
      "--active-index",
      `${activeIndex}`
    );
  })
);
!
999px

Console