在css中如何制作小型弹出模态框

<div class="modal-overlay">
  <div class="modal-content">
    <h3>提示</h3>
    <p>这是一个小型弹出框。</p>
    <button>关闭</button>
  </div>
</div>

.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
}

.modal-content {
  background: white;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  max-width: 300px;
  width: 100%;
  text-align: center;
}

.modal-content h3 {
  margin-top: 0;
  font-size: 18px;
  color: #333;
}

.modal-content button {
  margin-top: 10px;
  padding: 8px 16px;
  background-color: #007BFF;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

.modal-overlay {
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s ease;
}

.modal-overlay.show {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  transform: scale(0.9);
  transition: transform 0.3s ease;
}

.modal-overlay.show .modal-content {
  transform: scale(1);
}

// 显示模态框
document.querySelector('.modal-overlay').classList.add('show');

// 隐藏
document.querySelector('.modal-overlay').classList.remove('show');