「MENU → ×」に変化するハンバーガーメニュー

<div class="hamburger-wrapper">
  <button class="hamburger-text" id="hamburger-btn">
    <span class="text" data-text="×">MENU</span>
  </button>
  <nav class="hamburger-nav" id="hamburger-nav">
    <ul>
      <li><a href="#">TOP</a></li>
      <li><a href="#">SERVICE</a></li>
      <li><a href="#">WORKS</a></li>
      <li><a href="#">CONTACT</a></li>
    </ul>
  </nav>
</div>

.hamburger-wrapper {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 40px 0;
  position: relative;
}

.hamburger-text {
  background: none;
  border: none;
  font-size: 1.5rem;
  font-weight: bold;
  cursor: pointer;
  position: relative;
  padding: 0.6em 1em;
  z-index: 10;
  color: #333;
  transition: all 0.3s ease;
}

.hamburger-text .text::after {
  content: attr(data-text);
  position: absolute;
  top: 0;
  left: 0;
  width: 0;
  overflow: hidden;
  color: #d60000;
  transition: width 0.3s ease;
  white-space: nowrap;
}

.hamburger-text.active .text::after {
  width: 100%;
}

.hamburger-text.active .text {
  color: transparent;
}

.hamburger-nav {
  display: none;
  position: absolute;
  top: 120px;
  left: 50%;
  transform: translateX(-50%);
  width: 240px;
  background: #111;
  border: 1px solid #444;
  box-shadow: 0 2px 8px rgba(255,255,255,0.1);
}

.hamburger-nav.open {
  display: block;
}

.hamburger-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.hamburger-nav ul li a {
  display: block;
  padding: 14px 18px;
  text-decoration: none;
  color: #fff;
}

.hamburger-nav ul li a:hover {
  background: #333;
}

document.getElementById("hamburger-btn").addEventListener("click", function() {
  this.classList.toggle("active");
  document.getElementById("hamburger-nav").classList.toggle("open");
});