JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrap">
    <div id="pixelLeft">&nbsp;</div>
    <div id="bannerCenter">
      <img src="images/mybanner.png" />
    </div>
    <div id="pixelRight">&nbsp;</div>
</div>
<div style="clear:both;"></div>

CSS

*{
    margin:0;
    padding:0;
}
#bannerCenter{
    background:#ddd;
    width: 500px;
    float:left;
}
#pixelLeft{
    background:#999;
    float:left;
}
#pixelRight{
    background:#999;
    float:right;
}

#bannerCenter,#pixelLeft,#pixelRight{
    height: 400px;
}

JavaScript

$(document).ready(function() {
    $(window).on('resize', function() {
         $('#pixelLeft, #pixelRight').css('width',($('body').width()-$('#bannerCenter').width())/2);
    }).trigger('resize');      
});