spinner.css

.simple-chat .spinner {
    margin: auto;
    width: 100%;
    height: 100%;
    text-align: center;
}
.simple-chat .spinner > div {
    background-color: #333;
    height: 100%;
    width: 15%;
    display: inline-block;

    -webkit-animation: sk-stretchdelay 1.2s infinite ease-in-out;
    animation: sk-stretchdelay 1.2s infinite ease-in-out;
}

.simple-chat .spinner .rect2 {
    -webkit-animation-delay: -1.1s;
    animation-delay: -1.1s;
}

.simple-chat .spinner .rect3 {
    -webkit-animation-delay: -1.0s;
    animation-delay: -1.0s;
}

.simple-chat .spinner .rect4 {
    -webkit-animation-delay: -0.9s;
    animation-delay: -0.9s;
}

.simple-chat .spinner .rect5 {
    -webkit-animation-delay: -0.8s;
    animation-delay: -0.8s;
}

@-webkit-keyframes sk-stretchdelay {
    0%, 40%, 100% {
        -webkit-transform: scaleY(0.4)
    }
    20% {
        -webkit-transform: scaleY(1.0)
    }
}

@keyframes sk-stretchdelay {
    0%, 40%, 100% {
        transform: scaleY(0.4);
        -webkit-transform: scaleY(0.4);
    }
    20% {
        transform: scaleY(1.0);
        -webkit-transform: scaleY(1.0);
    }
}