CSS3飘动的云动画特效

手写动画特效天空中飘动的云，适合场景跟流动登陆等效果
.satic-area {
  position: relative;
  width: 100%;
  height: 100%;
  background: url(img/poster-about.jpg) no-repeat 100% 100%;
  background-size: cover;
}

.dynamic-area1   {
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  background: url(img/poster-drop-animate2.png) repeat-x 0px 0px;
  background-size: cover;
  animation: posterDrop1 6000s linear infinite;
}

@keyframes posterDrop1 {
  from { background-position: 0 0; }
  to { background-position: 4000% 0; }
}

.dynamic-area2   {
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  background: url(img/poster-drop-animate1.png) repeat-x 0px 0px;
  background-size: cover;
  animation: posterDrop2 8000s linear infinite;
}

@keyframes posterDrop2 {
  from { background-position: 0 0; }
  to { background-position: 30000% 0; }
}