JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
    <div id="panel">
        <div id="panel1" class="panelcell"></div>
        <div id="panel2" class="panelcell"></div>
        <div id="panel3" class="panelcell"></div>
        <div id="panel4" class="panelcell"></div>
        <div class="spacer" style="clear: both;"></div>
    </div>
</div>

CSS

#wrapper {
    width: 1280px;
}
#panel {
    width:100%;
}
#panel .panelcell {
    width: 25%;
    height: 213px;
    float: left;
    border-right: 1px solid white;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}
.panelcell {
    background-color: gray;
}
#panel1 {
    border-right: 1px solid white;
}