html {
    scroll-behavior: smooth;
}
.pagetop {
    height: 50px;
    width: 50px;
    position: fixed;
    left: 290px;
    bottom: 80px;
    background: #fff;
    border: solid 2px #000;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 2;
}

.pagetop_arrow {
    height: 10px;
    width: 10px;
    border-top: 3px solid #000;
    border-right: 3px solid #000;
    transform: translateY(20%) rotate(-45deg);
}