@keyframes grain {
    0% {
        transform: translate(20%, -15%)
    }
    10% {
        transform: translate(-20%, -15%)
    }
    20% {
        transform: translate(20%, -5%)
    }
    30% {
        transform: translate(-20%, -5%)
    }
    40% {
        transform: translate(20%, 5%)
    }
    50% {
        transform: translate(-20%, 5%)
    }
    60% {
        transform: translate(20%, 15%)
    }
    70% {
        transform: translate(-20%, 15%)
    }
    80% {
        transform: translate(20%, 5%)
    }
    90% {
        transform: translate(-20%, 5%)
    }
    100% {
        transform: translate(20%, -5%)
    }
}
.secao_conclusao::after {
    animation: grain 6s steps(10) infinite;
    content: "";
    width: 300%;
    height: 300%;
    background-image: url(../img/noise.png);
    background-repeat: repeat;
    position: absolute;
    left: -100%;
    top: -100%;
    opacity: 0.15;
    transition: opacity 0.4s ease;
    z-index: 1;
}