.loader {
    width: 150px;
    height: 150px;
    margin: 167px auto;
    transform: rotate(-45deg);
    font-size: 0;
    line-height: 0;
    animation: rotate-loader 5s infinite;
    padding: 25px;
    border: 1px solid #cf303d;
}

    .loader .loader-inner {
        position: relative;
        display: inline-block;
        width: 50%;
        height: 50%;
    }

    .loader .loading {
        position: absolute;
        background: #cf303d;
    }

    .loader .one {
        width: 100%;
        bottom: 0;
        height: 0;
        animation: loading-one 1s infinite;
    }

    .loader .two {
        width: 0;
        height: 100%;
        left: 0;
        animation: loading-two 1s infinite;
        animation-delay: 0.25s;
    }

    .loader .three {
        width: 0;
        height: 100%;
        right: 0;
        animation: loading-two 1s infinite;
        animation-delay: 0.75s;
    }

    .loader .four {
        width: 100%;
        top: 0;
        height: 0;
        animation: loading-one 1s infinite;
        animation-delay: 0.5s;
    }

@keyframes loading-one {
    0% {
        height: 0;
        opacity: 1;
    }

    12.5% {
        height: 100%;
        opacity: 1;
    }

    50% {
        opacity: 1;
    }

    100% {
        height: 100%;
        opacity: 0;
    }
}

@keyframes loading-two {
    0% {
        width: 0;
        opacity: 1;
    }

    12.5% {
        width: 100%;
        opacity: 1;
    }

    50% {
        opacity: 1;
    }

    100% {
        width: 100%;
        opacity: 0;
    }
}

@keyframes rotate-loader {
    0% {
        transform: rotate(-45deg);
    }

    20% {
        transform: rotate(-45deg);
    }

    25% {
        transform: rotate(-135deg);
    }

    45% {
        transform: rotate(-135deg);
    }

    50% {
        transform: rotate(-225deg);
    }

    70% {
        transform: rotate(-225deg);
    }

    75% {
        transform: rotate(-315deg);
    }

    95% {
        transform: rotate(-315deg);
    }

    100% {
        transform: rotate(-405deg);
    }
}