.flashing{
    background:#337ab7;
    padding:5px 10px;
    color:#fff;
    border:none;
    border-radius:5px;
    display:inline-block;
    animation-name: flash;
    animation-duration: 1s;
    animation-timing-function: linear;
    animation-iteration-count: infinite;

    /* Chrome 4+, Safari 4+, Opera 15+ */
    -webkit-animation-name: flash;
    -webkit-animation-duration: 1s;
    -webkit-animation-timing-function: linear;
    -webkit-animation-iteration-count: infinite;

    /* Firefox 5+ */
    -moz-animation-name: flash;
    -moz-animation-duration: 1s;
    -moz-animation-timing-function: linear;
    -moz-animation-iteration-count: infinite
}

@keyframes flash {
    0% { opacity: 1.0 }
    50% { opacity: 0.5 }
    100% { opacity: 1.0 }
}

/* Chrome 4+, Safari 4+, Opera 15+ */
@-webkit-keyframes flash {
    0% { opacity: 1.0 }
    50% { opacity: 0.5 }
    100% { opacity: 1.0 }
}

/* Firefox 5+ */
@-moz-keyframes flash {
    0% { opacity: 1.0 }
    50% { opacity: 0.5 }
    100% { opacity: 1.0 }
}