斜めに切り込むアニメーションメニュー

<div class="menu-wrapper">
  <button class="slice-button" id="menu-toggle">MENU</button>
  <nav class="slice-menu" id="slice-menu">
    <a href="#">TOP</a>
    <a href="#">ABOUT</a>
    <a href="#">WORKS</a>
    <a href="#">CONTACT</a>
  </nav>
</div>

.menu-wrapper {
  position: relative;
  text-align: center;
  margin-top: 40px;
}

.slice-button {
  background: #333;
  color: #fff;
  padding: 14px 28px;
  border: none;
  border-radius: 50px;
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
  transition: background 0.3s;
}
.slice-button:hover {
  background: #555;
}

.slice-menu {
  position: absolute;
  top: 60px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  gap: 12px;
  pointer-events: none;
  z-index: 10;
}

.slice-menu a {
  background: #222;
  color: #fff;
  text-decoration: none;
  padding: 10px 16px;
  border-radius: 20px;
  font-size: 1rem;
  opacity: 0;
  transform: rotateX(90deg) skewX(-15deg);
  transform-origin: left;
  transition: all 0.4s ease;
}

.slice-menu.open {
  pointer-events: auto;
}

.slice-menu.open a {
  opacity: 1;
  transform: rotateX(0deg) skewX(0deg);
}

.slice-menu.open a:nth-child(1) { transition-delay: 0.05s; }
.slice-menu.open a:nth-child(2) { transition-delay: 0.15s; }
.slice-menu.open a:nth-child(3) { transition-delay: 0.25s; }
.slice-menu.open a:nth-child(4) { transition-delay: 0.35s; }

const toggleBtn = document.getElementById("menu-toggle");
const menu = document.getElementById("slice-menu");

toggleBtn.addEventListener("click", () => {
  menu.classList.toggle("open");
  toggleBtn.textContent = menu.classList.contains("open") ? "CLOSE" : "MENU";
});