Kolay gelsin, "about" classindaki padding-top'i 10% yaparsaniz sorun cozulebilir.

@media screen and (min-width: 400px)

style.css:78
.about {
width: 100%;
background: #edbb4c;
position: relative;
text-align: center;
padding-top: 10%;
padding-bottom: 5%;

}