part of html
<div class="arrow content-header-arrow1">
                <img src="icons/arrow-down.svg" alt="scroll">
            </div>
            <div class="arrow content-header-arrow2">
                <img src="icons/arrow-down.svg" alt="scroll">
            </div>

css
.arrow {
    position: absolute;
    width: 100%;
    height: 100vh;
    z-index: 1;
    text-align: center;
}
.arrow img{
    opacity: 0;
    position: absolute;
    bottom: 5vh;
}
.content-header-arrow1 img {
    animation: arrow-movement 1.5s ease-in-out infinite; /* speed */
}
.content-header-arrow2 img{
    animation: arrow-movement 1.5s 0.75s ease-in-out infinite; /* speed - delay */
}
/* Animation */
@keyframes arrow-movement {
    0% {
        opacity: 0;
        bottom: 7vh;
    }
    70% {
        opacity: 1;
    }
    100% {
        opacity: 0;
    }
}