css3实现流星坠落效果

<div class="star"></div> ?????<div class="star pink"></div> ?????<div class="star blue"></div>

.star { ???display: block; ???width: 5px; ???height: 5px; ???border-radius: 50%; ???background: #FFF; ???top: 100px; ???left: 500px; ???position: relative; ???transform-origin: 100% 0; ???animation: star-ani 4s linear infinite; ???-webkit-animation:star-ani 5s linear infinite; ???box-shadow: 0 0 5px 5px rgba(255, 255, 255, .3); ???opacity: 0; ???z-index: 2;}.star:after { ???content: ‘‘; ???display: block; ???top: 0px; ???left: 4px; ???border: 0px solid #fff; ???border-width: 0px 90px 2px 90px; ???border-color: transparent transparent transparent rgba(255, 255, 255, .3); ???transform: rotate(-45deg) translate3d(1px, 3px, 0); ???box-shadow: 0 0 1px 0 rgba(255, 255, 255, .1); ???transform-origin: 0% 100%; ???animation: shooting-ani 3s infinite ease-out;}.pink { ???top: 100px; ???left: 800px; ???background: #fff; ???animation-delay: 3s; ???-webkit-animation-delay: 3s; ???-moz-animation-delay: 3s;}.pink:after { ???border-color: transparent transparent transparent #fff; ???animation-delay: 3s; ???-webkit-animation-delay: 3s; ???-moz-animation-delay: 3s;}.blue { ???top: 120px; ???left: 1200px; ???background: fff; ???animation-delay: 7s; ???-webkit-animation-delay: 7s; ???-moz-animation-delay: 7s;}.blue:after { ????border-color: transparent transparent transparent fff; ???-webkit-animation-delay: 7s; ???-moz-animation-delay: 7s; ???animation-delay: 7s;} ?@keyframes star-ani { ???0% { ???????opacity: 0; ???????transform: scale(0) translate3d(0, 0, 0); ???} ???20%{ ???????opacity: 0.8; ???????transform: scale(0.2) translate3d(-100px, 100px, 0); ???} ???40% { ???????opacity: 0.8; ???????transform: scale(0.4) translate3d(-200px, 200px, 0); ???} ???60% { ???????opacity: 0.8; ???????transform: scale(0.6) translate3d(-300px, 300px, 0); ???} ???80% { ???????opacity: 1; ???????transform: scale(1) translate3d(-350px, 350px, 0); ???} ???100% { ???????opacity: 1; ???????transform: scale(1.2) translate3d(-400px, 380px, 0); ???}}