.back-loader { 
    height: 100%;
    width: 100%;
    position: fixed;
    background: rgba(0,0,0,0.6);
    z-index: 999999;
    top: 0;
}

.loader
{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%) rotate(45deg);

    width: 100vw;
    animation: animate 1s linear infinite;

    z-index: 999999;
}

.loader span
{
    position: absolute;
    width: 50px;
    height: 50px;
    background: #f00;

    animation: rotate 1s linear infinite;

    z-index: 9999;
}

.loader span:nth-child(1) 
{
    top: 0;
    left: 0;
    background: #f79f1f;
}

.loader span:nth-child(2) 
{
    top: 0;
    right: 0;
    background: #12cbc4;
}

.loader span:nth-child(3) 
{
    bottom: 0;
    left: 0;
    background: #ed4c67;
}


.loader span:nth-child(4) 
{
    bottom: 0;
    right: 0;
    background: #a3cb38;
}

@keyframes animate
{
    0%
    {
        width: 100px;
        height: 100px;
    }

    10%
    {
        width: 100px;
        height: 100px;
    }

    50%
    {
        width: 150px;
        height: 150px;
    }

    90%
    {
        width: 100px;
        height: 100px;
    }

    100%
    {
        width: 100px;
        height: 100px;
    }
}


@keyframes rotate
{
    0%
    {
       transform: rotate(0deg);
    }

    10%
    {
        transform: rotate(0deg);
    }

    50%
    {
        transform: rotate(90deg);
    }

    90%
    {
        transform: rotate(90deg);
    }

    100%
    {
        transform: rotate(90deg);
    }
}