body {
  background: #191819;
  overflow: hidden;
}

.scroll_example {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
}

.scroll_nav {
    width: 100%;
}

.scroll_nav a {
    display: inline-block;
    text-decoration: none;
    text-align: center;
    color: #fff;
    width: calc(100% / 3 - 5px);
    background: #222;
    padding: 10px 0;
}

.scroll_nav a:nth-child(2) {
    background: #1d1d1d;
}

.scroll_cnt {
    display: block;
    color: #fff;
    width: 100%;
    height: 150px;
    overflow-y: scroll;
    scroll-behavior: smooth;
}

.scroll_cnt div {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
    font-size: 5em;
}

.scroll_cnt div:nth-child(1) {
    background: #333;
}

.scroll_cnt div:nth-child(2) {
    background: #444;
}

.scroll_cnt div:nth-child(3) {
    background: #555;
}