JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://www.flotcharts.org/flot/jquery.flot.js"></script>
After:
<div id="flot_chart" style="width:400px;height:400px;overflow: hidden;"></div>

Before:
<div id="flot_chart_before" style="width:400px;height:400px;overflow: hidden;"></div>

CSS

#flot_chart div.xAxis div.tickLabel 
{
    transform: rotate(-90deg);
    -ms-transform:rotate(-90deg); /* IE 9 */
    -moz-transform:rotate(-90deg); /* Firefox */
    -webkit-transform:rotate(-90deg); /* Safari and Chrome */
    -o-transform:rotate(-90deg); /* Opera */
    /*rotation-point:50% 50%;*/ /* CSS3 */
    /*rotation:270deg;*/ /* CSS3 */
}
#flot_chart_before div.xAxis div.tickLabel 
{
    transform: rotate(-90deg);
    -ms-transform:rotate(-90deg); /* IE 9 */
    -moz-transform:rotate(-90deg); /* Firefox */
    -webkit-transform:rotate(-90deg); /* Safari and Chrome */
    -o-transform:rotate(-90deg); /* Opera */
    /*rotation-point:50% 50%;*/ /* CSS3 */
    /*rotation:270deg;*/ /* CSS3 */
}

JavaScript

var d2 = [[0, 3], [1, 8], [2, 5]];

options = {
    xaxis: {
        ticks: [[0,"LongTick"],[1,"LongerTick"],
                [2,"LongerLongerTick"]]
    }
    
};

$.plot("#flot_chart_before", [ d2 ], options);

$.plot("#flot_chart", [ d2 ], options);

// find longest label height
// also push the labels down half their width
var longest = -1;
$('#flot_chart .xAxis .tickLabel').each(function(){
   var self = $(this);
   var width = self.width();
   self.css('top',parseInt(self.css('top')) + width/2 - 5);
    if (width > longest){
        longest = width;
    }
});

// now adjust the chart height so we don't overlflow
$("#flot_chart").height($("#flot_chart").height() + longest - $('#flot_chart .xAxis .tickLabel').height() + 5);