HTML按钮不能与css背景重叠

<div class="container">
  <button class="transparent-button">按钮</button>
</div>

<style>
.container {
  background-color: #f1f1f1;
  padding: 10px;
}

.transparent-button {
  background-color: transparent;
  border: none;
  color: white;
  padding: 10px 20px;
}
</style>

<div class="container">
  <button class="overlay-button">按钮</button>
</div>

<style>
.container {
  position: relative;
  background-image: url("背景图片地址");
  background-size: cover;
  height: 300px;
}

.overlay-button {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background-color: #f1f1f1;
  border: none;
  color: white;
  padding: 10px 20px;
}
</style>