JSFiddle - React, Tailwind, and code Playground

HTML

<div class="appointmentDetails">
  <div class="staffInfo">
    <div>Dr John Doe</div>
  </div>
  <div class="appointmentInfo">
    <ul>
      <li>
        <div></div>
      </li>
      <li class="timeSlots bg">
        <div><a href="#">08:00</a></div>
        <div><a href="#">09:00</a></div>
        <div><a href="#">10:00</a></div>
        <div><a href="#">11:00</a></div>
        <div><a href="#">12:00</a></div>
        <div><a href="#">13:00</a></div>
        <div><a href="#">14:00</a></div>
        <div><a href="#">15:00</a></div>
        <div><a href="#">16:00</a></div>
        <div><a href="#">17:00</a></div>
        <div><a href="#">18:00</a></div>
      </li>
      <li class="timeSlots">
        <div><a href="#">08:00</a></div>
        <div><a href="#">09:00</a></div>
        <div><a href="#">10:00</a></div>
        <div><a href="#">11:00</a></div>
        <div><a href="#">12:00</a></div>
        <div><a href="#">13:00</a></div>
        <div><a href="#">14:00</a></div>
        <div><a href="#">15:00</a></div>
        <div><a href="#">16:00</a></div>
        <div><a href="#">17:00</a></div>
        <div><a href="#">18:00</a></div>
      </li>
      <li class="timeSlots bg">
        <div><a href="#">08:00</a></div>
        <div><a href="#">09:00</a></div>
        <div><a href="#">10:00</a></div>
        <div><a href="#">11:00</a></div>
        <div><a href="#">12:00</a></div>
        <div><a href="#">13:00</a></div>
        <div><a href="#">14:00</a></div>
        <div><a href="#">15:00</a></div>
        <div><a href="#">16:00</a></div>
        <div><a href="#">17:00</a></div>
        <div><a href="#">18:00</a></div>
      </li>
      <li class="timeSlots">
        <div><a href="#">08:00</a></div>
      </li>
      <li class="timeSlots bg">
        <div><a href="#">09:00</a></div>
      </li>
      <li class="timeSlots">
        <div><a href="#">09:00</a></div>
      </li>
      <li class="timeSlots bg">
        <div><a href="#">08:00</a></div>
      </li>
  ...

CSS

.appointmentNav, .appointmentDetails {
	clear: both;
}
.appointmentsNav {
	vertical-align: middle;
	border-bottom: 1px solid #ccc;
	overflow: auto;
}
.searchInfo, .dayInfo {
}
.searchInfo, .staffInfo {
	width: 200px;
	float: left;
}
.dayInfo, .appointmentInfo {
	text-align: center;
}
.dayInfo li.bg, .appointmentInfo li.bg {
	background-color: #F7F7F7;
}
.dayInfo ul, .appointmentInfo ul {
	float: left;
	margin: 0 0 0 11px;
}
.dayInfo li, .appointmentInfo li {
	float: left;
	font-weight: bold;
	height: auto;
	padding: 5px;
	width: 55px;
	list-style-type: none;
}
.appointmentInfo li {
	min-height: 100px;
	overflow: auto;
}
.appointmentDetails {
	border-bottom: 1px solid #ccc;
	overflow: auto;
}

JavaScript

var maxHeight = 0;
function setHeight(column) {
    //Get all the element with class = col
    column = $(column);
    //Loop all the column
    column.each(function() {       
        //Store the highest value
        if($(this).height() > maxHeight) {
            maxHeight = $(this).height();;
        }
    });
    //Set the height
    column.height(maxHeight);
}

setHeight('.appointmentInfo li');