SOURCE

cont body = document.querySelector('.body')

<div class="body"></div>
<div class="tabbar">
    <div class="common-button"></div>
    <div class="common-button"></div>
    <div class="center-button"></div>
    <div class="common-button"></div>
    <div class="common-button"></div>
</div>

.body {
    width: 100vw;
    height: 30vw;
    background-color: lightblue;
    overflow-y: scroll;
    padding: 1rem;
    color: lightcyan;
}

.tabbar {
    width: 100vw;
    height: 10vw;
    padding: 5vw 0;
    background-color: lightcoral;
    display: flex;
    justify-content: space-evenly;
}

.common-button {
    width: 10vw;
    height: 10vw;
    background-color: lightskyblue;
}

.center-button {
    width: 20vw;
    height: 20vw;
    position: relative;
    top: -10vw;
    background-color: lightcyan;
}