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Adding Classes

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About the <head>

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CSS

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CSS Base

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JavaScript

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HTML 

              
                <main>
  <header>
    <h2><span>Table</span> of content</h2>
  </header>
  <section>
    <ul class='indexes'>
      <li data-index='0'>01</li>
      <li data-index='1'>02</li>
      <li data-index='2'>03</li>
      <li data-index='3'>04</li>
    </ul>
    <ul class='tabs'>
      <li class='tab'>
        <article class='tab-content'>
          <h3>Midnight Station</h3>
          <p>Lorem ipsum dolor, sit amet consectetur adipisicing elit.
          Voluptas nihil sequi doloribus obcaecati. Aut vel, recusandae ipsa
          voluptate blanditiis nemo magnam sit modi architecto officia
          maiores magni. Necessitatibus, iste aut.</p>
          <button>Read More</button>
        </article>
        <div class='tab-image'><img src='https://picsum.photos/id/345/1000/600'></div>
      </li>
      <li class='tab'>
        <article class='tab-content'>
          <h3>The Hitchhiker</h3>
          <p>Lorem ipsum dolor, sit amet consectetur adipisicing elit.
          Voluptas nihil sequi doloribus obcaecati. Aut vel, recusandae ipsa
          voluptate blanditiis nemo magnam sit modi architecto officia
          maiores magni. Necessitatibus, iste aut.</p>
          <button>Read More</button>
        </article>
        <div class='tab-image'><img src='https://picsum.photos/id/352/1000/600'></div>
      </li>
      <li class='tab'>
        <article class='tab-content'>
          <h3>Missing Pages</h3>
          <p>Lorem ipsum dolor, sit amet consectetur adipisicing elit.
          Voluptas nihil sequi doloribus obcaecati. Aut vel, recusandae ipsa
          voluptate blanditiis nemo magnam sit modi architecto officia
          maiores magni. Necessitatibus, iste aut.</p>
          <button>Read More</button>
        </article>
        <div class='tab-image'><img src='https://picsum.photos/id/444/1000/600'></div>
      </li>
      <li class='tab'>
        <article class='tab-content'>
          <h3>Uninvited Guests</h3>
          <p>Lorem ipsum dolor, sit amet consectetur adipisicing elit.
          Voluptas nihil sequi doloribus obcaecati. Aut vel, recusandae ipsa
          voluptate blanditiis nemo magnam sit modi architecto officia
          maiores magni. Necessitatibus, iste aut.</p>
          <button>Read More</button>
        </article>
        <div class='tab-image'><img src='https://picsum.photos/id/451/1000/600'></div>
      </li>
    </ul>
  </section>
</main>
!

CSS 

              
                :root {
  --primary: rgb(211,38,38);
  --overlay: rgba(211,38,38,0.6);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  height: 100vh;
  display: grid;
  place-items: center;
  background-color: black;
  color: rgba(255,255,255,0.85);
}

main {
  width: 600px;
  height: 300px;
  font: 0.7rem impact,sans-serif;

  & header {
    font-size: 1.2rem;
    text-transform: uppercase;
    margin-bottom: 2.25rem;
    color: white;

    & span {
      color: var(--primary);
    }
  }

  & section {
    display: flex;
    gap: 2rem;
  }
}

.indexes, .tabs { list-style-type: none; }

.indexes {
  font-size: 1rem;

  & li {
    padding: 1rem;
    border: 1px solid transparent;
    cursor: pointer;
  }
}

.tabs { position: relative; }

.tab {
  position: absolute;
  display: flex;
  width: 530px;
  height: 225px;
  opacity: 0; 
  background-color: black;
  overflow: hidden;
}

.tab-content {
  position: relative;
  z-index: 5;
  width: 300px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 1rem;
  opacity: 0;
  transform: translateY(-5rem);

  & h3 {
    font-family: helvetica;
    font-weight: 900;
    font-size: 1rem;
    border-bottom: 1.5px solid white;
    padding-bottom: 1rem;
  }

  & p {
    font-family: helvetica;
    font-weight: 100;
    line-height: 2;
    color: rgba(255,255,255,0.7);
  }

  & button {
    width: fit-content;
    background-color: transparent;
    color: white;
    border: 1px solid white;
    font-size: 0.7rem;
    padding: 0.75rem 1rem;
    cursor: pointer;
  }
}

@keyframes content {
  100% {
    opacity: 1;
    transform: translateY(0);
  }
}

.tab-image {
  position: absolute;
  right: 1rem;
  width: 200px;
  height: 200px;
  opacity: 0;
  transform: translateX(2rem);

  &::after {
    content: '';
    position: absolute;
    inset: 0;
    background-color: var(--overlay);
    mix-blend-mode: multiply;
  }

  & img {
    width: inherit;
    height: inherit;
    object-fit: cover;
    filter: grayscale(100%);
  }
}

@keyframes image {
  100% {
    opacity: 1;
    width: 300px;
    transform: translateX(0);
  }
}

.active .tab          { opacity: 1; z-index: 5; }
.active .tab-content  { animation: content 0.9s ease-out 0.4s forwards; }
.active .tab-image    { animation: image 1s ease-out forwards; }
!

JS 

              
                const indexes = document.querySelectorAll('.indexes li');
const tabs = document.querySelectorAll('.tab');
const contents = document.querySelectorAll('.tab-content');

function reset() {
  for (let i = 0; i < tabs.length; i++) {
    indexes[i].style.borderColor = 'transparent';
    tabs[i].style.zIndex = 0;
    tabs[i].classList.remove('active');
    contents[i].classList.remove('active');
  }
}

function showTab(i) {
  indexes[i].style.borderColor = 'rgba(211,38,38,0.6)';
  tabs[i].style.opacity = 1;
  tabs[i].style.zIndex = 5;
  tabs[i].classList.add('active');
  contents[i].classList.add('active');
}

function activate(e) {
  if (!e.target.matches('.indexes li')) return;
  reset();
  showTab(e.target.dataset.index);
}

const init = () => showTab(0);

window.addEventListener('load',init,false);
window.addEventListener('click',activate,false);
!
999px

Console