将按钮放到下一行和中心位置。保持背景图像为全尺寸

<div class="container">
  <div class="background-image"></div>
  <div class="button-wrapper">
    <button class="centered-button">按钮</button>
  </div>
</div>

.container {
  position: relative;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.background-image {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: url('背景图像路径');
  background-size: cover;
  z-index: -1;
}

.button-wrapper {
  display: flex;
  justify-content: center;
}

.centered-button {
  padding: 10px 20px;
  font-size: 16px;
  background-color: #ccc;
  border: none;
  border-radius: 5px;
}