如何用CSS动画实现雪花飘落效果 CSS动画模拟自然缓慢下降动效

<div class="snow-container">
  <div class="snow"></div>
  <div class="snow"></div>
  <div class="snow"></div>
  <div class="snow"></div>
  <div class="snow"></div>
  <!-- 更多雪花元素 -->
</div>

body {
  background-color: #222; /* 模拟夜空或深色背景 */
  overflow: hidden; /* 防止雪花超出边界产生滚动条 */
  height: 100vh;
  margin: 0;
  position: relative;
}

.snow-container {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none; /* 确保雪花不会阻碍鼠标事件 */
}

.snow {
  position: absolute;
  background-color: rgba(255, 255, 255, 0.8); /* 雪花颜色，带透明度 */
  border-radius: 50%;
  pointer-events: none;
  /* 初始随机位置和大小，实际应用中会通过JS动态设置 */
  width: 5px;
  height: 5px;
  opacity: 0; /* 初始不可见 */
  animation: snowfall linear infinite;
}

/* 关键帧动画 */
@keyframes snowfall {
  0% {
    transform: translateY(-10vh) translateX(0); /* 从屏幕上方开始 */
    opacity: 0;
  }
  20% {
    opacity: 0.8; /* 逐渐显现 */
  }
  100% {
    transform: translateY(100vh) translateX(50px); /* 飘落到底部，并略微横向偏移 */
    opacity: 0; /* 逐渐消失 */
  }
}

/* 为每个雪花设置不同的动画属性以增加随机性 */
.snow:nth-child(1) {
  left: 10%;
  animation-duration: 15s;
  animation-delay: 0s;
  width: 8px;
  height: 8px;
}
.snow:nth-child(2) {
  left: 25%;
  animation-duration: 12s;
  animation-delay: 2s;
  width: 6px;
  height: 6px;
  opacity: 0.6; /* 初始透明度可以不同 */
}
.snow:nth-child(3) {
  left: 40%;
  animation-duration: 18s;
  animation-delay: 4s;
  width: 4px;
  height: 4px;
}
.snow:nth-child(4) {
  left: 60%;
  animation-duration: 10s;
  animation-delay: 1s;
  width: 7px;
  height: 7px;
  opacity: 0.7;
}
.snow:nth-child(5) {
  left: 80%;
  animation-duration: 16s;
  animation-delay: 3s;
  width: 5px;
  height: 5px;
}
/* ... 更多雪花 ... */