css动画在微信中显示会多出一个角，电脑上看则正常

问题：

微信里播放动画 no-repeat 好像没效果？
在PC的浏览器正常，放到微信里就出问题。

CSS动画是这样写的：

@keyframes dice1
{
    0% {background: url(../images/dice1.png) no-repeat center; background-size: contain; }
    20% {background: url(../images/dice5.png) no-repeat center; background-size: contain; }
    40% {background: url(../images/dice3.png) no-repeat center; background-size: contain; }
    60% {background: url(../images/dice6.png) no-repeat center; background-size: contain; }
    80% {background: url(../images/dice2.png) no-repeat center; background-size: contain; }
    100% {background: url(../images/dice4.png) no-repeat center; background-size: contain; }
}

@keyframes dice2
{
    0% {background: url(../images/dice5.png) no-repeat center; background-size: contain; }
    20% {background: url(../images/dice2.png) no-repeat center; background-size: contain; }
    40% {background: url(../images/dice3.png) no-repeat center; background-size: contain; }
    60% {background: url(../images/dice6.png) no-repeat center; background-size: contain; }
    80% {background: url(../images/dice4.png) no-repeat center; background-size: contain; }
    100% {background: url(../images/dice1.png) no-repeat center; background-size: contain; }
}

@-webkit-keyframes dice1
{
    0% {background: url(../images/dice1.png) no-repeat center; background-size: contain; }
    20% {background: url(../images/dice5.png) no-repeat center; background-size: contain; }
    40% {background: url(../images/dice3.png) no-repeat center; background-size: contain; }
    60% {background: url(../images/dice6.png) no-repeat center; background-size: contain; }
    80% {background: url(../images/dice2.png) no-repeat center; background-size: contain; }
    100% {background: url(../images/dice4.png) no-repeat center; background-size: contain; }
}

@-webkit-keyframes dice2
{
    0% {background: url(../images/dice5.png) no-repeat center; background-size: contain; }
    20% {background: url(../images/dice2.png) no-repeat center; background-size: contain; }
    40% {background: url(../images/dice3.png) no-repeat center; background-size: contain; }
    60% {background: url(../images/dice6.png) no-repeat center; background-size: contain; }
    80% {background: url(../images/dice4.png) no-repeat center; background-size: contain; }
    100% {background: url(../images/dice1.png) no-repeat center; background-size: contain; }
}

引用动画

.ani1 { -webkit-animation: dice1 .5s step-start infinite; animation: dice1 .5s step-start infinite; }
.ani2 { -webkit-animation: dice2 .5s step-start infinite; animation: dice2 .5s step-start infinite; }

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谢谢邀请。二维码扫描一片空白啊！