JSFiddle - React, Tailwind, and code Playground

HTML

<div class="buttons">
        <button>Reddit</button>
        <button>G+</button>
        <button>Facebook</button>
        <button>Stack Exchange</button>
        <button>Twitter</button>
        <button>Steam</button>
</div>

CSS

.buttons {
    text-align: center;
    background: #bada55;
    margin:0 auto;
    overflow:hidden;
}
button {
    font-size:20px;
}

JavaScript

var buttons = document.querySelector(".buttons");

function distribute(){
    buttons.style.width = "auto";
    var height = buttons.offsetHeight;
    do{
        buttons.style.width = buttons.offsetWidth - 1 + "px";
        if(buttons.scrollWidth > buttons.offsetWidth) break;
    }
    while(buttons.offsetHeight == height);
    buttons.style.width = buttons.offsetWidth + 1 + "px";
}
distribute();
window.addEventListener("resize", distribute);