.ubaAudioButton {
    background: url('../design/bt_ouvir_ico.png') no-repeat center center;
    display: inline-block;
    width: 22px;
    height: 22px;
    overflow: hidden;
    margin: 5px;
    color: transparent !important;
    vertical-align: top !important;
}
.ubaAudioButton.loading {
    opacity: 0.5;
}
.ubaAudioButton.playing, .ubaAudioButton.loading {
    -webkit-animation-name:             rotate; 
    -webkit-animation-duration:         1s; 
    -webkit-animation-iteration-count:  infinite;
    -webkit-transition-timing-function: linear;    
}

@-webkit-keyframes rotate {
    from {
        -webkit-transform: rotate(0deg);
    }
    to { 
        -webkit-transform: rotate(360deg);
    }
}