css3中的微调器实现

Question

我正在尝试在css3中实现微调器。一切正常，除了白色方块显示重叠的微调圆圈。如下图所示。 （浏览器：Firefox 25.0.1）

Css： -

.spinner {
    height: 30px;
    width: 30px;
    margin: 0px auto;
    position: relative;
    -webkit-animation: rotation .6s infinite linear;
    -moz-animation: rotation .6s infinite linear;
    -o-animation: rotation .6s infinite linear;
    animation: rotation .6s infinite linear;
    border-left: 3px solid rgba(0, 0, 0, .15);
    border-right: 3px solid rgba(0, 0, 0, .15);
    border-bottom: 3px solid rgba(0, 0, 0, .15);
    border-top: 3px solid rgba(0, 0, 0, .8);
    border-radius: 100%;
}
@-webkit-keyframes rotation {
    from {
    -webkit-transform: rotate(0deg);
    }
    to {
    -webkit-transform: rotate(359deg);
    }
}
@-moz-keyframes rotation {
    from {
    -moz-transform: rotate(0deg);
    }
    to {
    -moz-transform: rotate(359deg);
    }
}
@-o-keyframes rotation {
    from {
    -o-transform: rotate(0deg);
    }
    to {
    -o-transform: rotate(359deg);
    }
}
@keyframes rotation {
    from {
    transform: rotate(0deg);
    }
    to {
    transform: rotate(359deg);
    }
}

Fiddle My Browser Info