1 - arborescence en css uniquement
 .tree {
  --spacing: 1.5rem;
  --radius: 10px;
  --marker-bg-default: #ddd;
  --marker-bg-haschild: #6b9abb;
  line-height: 2rem;
}
.tree li {
  display: block;
  position: relative;
  padding-left: calc(2 * var(--spacing) - var(--radius) - 2px);
}
.tree ul {
  margin-left: calc(var(--radius) - var(--spacing));
  padding-left: 0;
}
.tree ul li {
  border-left: 2px solid #ddd;
}
.tree ul li:last-child {
  border-color: transparent;
}
.tree ul li::before {
  content: "";
  display: block;
  position: absolute;
  top: calc(var(--spacing) / -2);
  left: -2px;
  width: calc(var(--spacing) + 2px);
  height: calc(var(--spacing) + 1px);
  border: solid #ddd;
  border-width: 0 0 2px 2px;
}
.tree summary {
  display: block;
  cursor: pointer;
}
.tree summary::marker,
.tree summary::-webkit-details-marker {
  display: none;
}
.tree summary:focus {
  outline: none;
}
.tree summary:focus-visible {
  outline: 1px dotted #000;
}
.tree li::after,
.tree summary::before {
  content: "";
  display: block;
  position: absolute;
  top: calc(var(--spacing) / 2 - var(--radius) + 2px);
  left: calc(var(--spacing) - var(--radius) - 2px);
  width: calc(2 * var(--radius));
  height: calc(2 * var(--radius));
  border-radius: 50%;
  background: var(--marker-bg-default);
}
.tree summary::before {
  content: "+";
  z-index: 1;
  background: var(--marker-bg-haschild);
  color: #fff;
  line-height: calc(2 * var(--radius));
  text-align: center;
}
.tree details[open] > summary::before {
  content: "−";
}






<ul class="tree">
  <li>
    <details open>
      <summary>Informatique</summary>
      <ul>
        <li>
          <details>
            <summary>Périphériques</summary>
            <ul>
              <li>Clavier</li>
              <li>Souris</li>
              <li>Ecran</li>
            </ul>
          </details>
        </li>
        <li>
          <details open>
            <summary>Stockage</summary>
            <ul>
              <li>Disque dur</li>
              <li>SSD</li>
              <li>Clé USB</li>
            </ul>
          </details>
        </li>
        <li>
          <details>
            <summary>Composants</summary>
            <ul>
              <li>Processeur</li>
              <li>Carte mère</li>
              <li>Mémoire</li>
              <li>
            </ul>
          </details>
        </li>
        <li>
          <details>
            <summary>Composants</summary>
            <ul>
              <li>Processeur</li>
              <li>Carte mère</li>
              <li>Mémoire</li>
              <li>Carte graphique</li>
            </ul>
          </details>
        </li>
      </ul>
    </details>
  </li>
</ul>
</code></pre> codeCarte graphique</li>
            </ul>
          </details>
        </li>
      </ul>
    </details>
  </li>
</ul>