JSFiddle - React, Tailwind, and code Playground

HTML

<div class='container'>
    <div class='inner' style='background : #FF0000;'></div>
    <div class='inner' style='background : #00FF00;'></div>
    <div class='inner' style='background : #0000FF;'></div>
    <div class='inner' style='background : orange;'></div>
</div>

CSS

.container {
    width: 550px;
    height: 150px;
    background : #bbb;
}
.inner {
    float:left;
    height:100%;
    min-width:30px;
}

JavaScript

var containerW = $('.container').width();
var innerCount = $('.container .inner').length;

$('.inner').css({
    width: containerW / innerCount
})