<div class="container">
  <ul>
    <li>W3cplus.com</li>
  </ul>
</div>

<div class="form">
  <label for="content">content:</label>
  <select name="content" id="contet">
    <optgroup label="Single String">
      <option value="'A'">A</option>
      <option value="'➤'">➤</option>
      <option value="'🔥'">🔥</option>
      <option value="'\2762'">'\2762'</option>
      <option value="'\01F33A'">'\01F33A'</option>
    </optgroup>
    <optgroup label="Multiple Strings">
      <option value="'A' 'B'">'A' 'B'</option>
      <option value="'A ' ' B'">'A ' ' B'</option>
      <option value="'❢' '𝄞'">'❢' '𝄞'</option>
      <option value="'❢ ' ' 𝄞'">'❢' '𝄞'</option>
      <option value="'🐻' '🐶'">'🐻' '🐶'</option>
      <option value="'🍔' '𝄫'">'🍔' '𝄫'</option>
      <option value="'\2763' '\2141'">'\2763' '\2141'</option>
      <option value="'\01F42C' '\01F41F'">'\01F42C' '\01F41F'</option>
    </optgroup>
  </select>
</div>

@import url("https://fonts.googleapis.com/css2?family=Exo:wght@600&display=swap");

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

body {
  inline-size: 100vw;
  min-block-size: 100vh;

  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  font-family: "Exo", Arial, sans-serif;
  background-color: #f7f7f7;
  line-height: 2;
}

.container {
  padding: 40px;
  background: #fff;
  box-sizing: border-box;
  box-shadow: 0 2px 4px rgb(0 0 0 / 20%);
  min-width: 40vw;
  max-width: 40vw;
  border-radius: 5px;
  position: relative;
}

:root {
  --content: "A";
}

li::marker,
li::after {
  content: var(--content);
}

const rootEle = document.documentElement;
const select = document.getElementById("contet");

select.addEventListener("change", (etv) => {
  rootEle.style.setProperty("--content", etv.target.value);
});