JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>


<html>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link href="https://fonts.googleapis.com/css?family=Raleway" rel="stylesheet">
<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/smoothness/jquery-ui.css" />
<link rel="stylesheet" href="styles.css" />
<script src="http://code.jquery.com/jquery-1.9.1.js"></script>
<script src="http://code.jquery.com/ui/1.10.3/jquery-ui.js"></script>
<script>

var currentTab = 0; // Current tab is set to be the first tab (0)
showTab(currentTab); // Display the current tab

function showTab(n) {
  // This function will display the specified tab of the form...
  var x = document.getElementsByClassName("tab");
  x[n].style.display = "block";
  //... and fix the Previous/Next buttons:
  if (n == 0) {
    document.getElementById("prevBtn").style.display = "none";
  } else {
    document.getElementById("prevBtn").style.display = "inline";
  }
  if (n == (x.length - 1)) {
    document.getElementById("nextBtn").innerHTML = "Submit";
  } else {
    document.getElementById("nextBtn").innerHTML = "Next";
  }
  //... and run a function that will display the correct step indicator:
  fixStepIndicator(n)
}

function nextPrev(n) {
  // This function will figure out which tab to display
  var x = document.getElementsByClassName("tab");
  // Exit the function if any field in the current tab is invalid:
   if (n == 1 && !validateForm()) return false;
  // Hide the current tab:
  x[currentTab].style.display = "none";
  // Increase or decrease the current tab by 1:
  currentTab = currentTab + n;
  // if you have reached the end of the form...
  if (currentTab >= x.length) {
    // ... the form gets submitted:
    document.getElementById("regForm").submit();
    // onclick="alert('Form submitted successfully!');"
    return false;
  }
  // Otherwise, display the correct tab:
  showTab(currentTab);
}

function validateForm() {
  // This function deals with validation of the form fields
 ...

CSS

* {
  box-sizing: border-box;
}

body {
  background-color: #f1f1f1;
}

#regForm {
  background-color: #ffffff;
  margin: 100px auto;
  font-family: Raleway;
  padding: 40px;
  width: 70%;
  min-width: 300px;
}

h1 {
  text-align: center;  
}

input {
  padding: 10px;
  width: 100%;
  font-size: 17px;
  font-family: Raleway;
  border: 1px solid #aaaaaa;
}
textarea {
  padding: 10px;
  width: 100%;
  font-size: 17px;
  font-family: Raleway;
  border: 1px solid #aaaaaa;
}


/* Mark input boxes that gets an error on validation: */
input.invalid {
  background-color: #ffdddd;
}
textarea.invalid {
  background-color: #ffdddd;
}
select.invalid {
  background-color: #ffdddd;
}

/* Hide all steps by default: */
.tab {
  display: none;
}

button {
  background-color: #4CAF50;
  color: #ffffff;
  border: none;
  padding: 10px 20px;
  font-size: 17px;
  font-family: Raleway;
  cursor: pointer;
}

button:hover {
  opacity: 0.8;
}

#prevBtn {
  background-color: #bbbbbb;
}
#tax-id {
  width: 15%;
}
#asterisk {
    position: relative;
    color: red;
    font-size: 20pt;
    bottom: -6px;
}
#asterisk-TAX {
  position: relative;
  color: red;
  font-size: 12pt;
  bottom: -6px;
}
#required{
  color: red;
  font-size: 22px;
}

/* Make circles that indicate the steps of the form: */
.step {
  height: 15px;
  width: 15px;
  margin: 0 2px;
  background-color: #bbbbbb;
  border: none;  
  border-radius: 50%;
  display: inline-block;
  opacity: 0.5;
}

.step.active {
  opacity: 1;
}
.wrapper-class input[type="radio"] {
  width: 15px;
  
}
#subhead {
    position: relative;
    bottom: 14px;
    text-align: center;
}
#attendees {
  width: 10%;
  margin-top:3px;
}
#resetBtn {
  width: 62%;
  margin-top: 5px;
}
#regForm > div > div {
  margin-bottom: 15px;
}
#datepicker {
  width:20%;
}

#datepicker2 {
  width:20%;
}

#datepicker3 {
  width:20%;
}

#datepicker4 {
  width:20%;
}
.wrapper-class p {
  display: inline;
  margin-left: 5px;
  }
  .reveal-if-active {
	opacity: 0;
	max-height:...

JavaScript

var currentTab = 0; // Current tab is set to be the first tab (0)
showTab(currentTab); // Display the current tab

function showTab(n) {
  // This function will display the specified tab of the form...
  var x = document.getElementsByClassName("tab");
  x[n].style.display = "block";
  //... and fix the Previous/Next buttons:
  if (n == 0) {
    document.getElementById("prevBtn").style.display = "none";
  } else {
    document.getElementById("prevBtn").style.display = "inline";
  }
  if (n == (x.length - 1)) {
    document.getElementById("nextBtn").innerHTML = "Submit";
  } else {
    document.getElementById("nextBtn").innerHTML = "Next";
  }
  //... and run a function that will display the correct step indicator:
  fixStepIndicator(n)
}

function nextPrev(n) {
  // This function will figure out which tab to display
  var x = document.getElementsByClassName("tab");
  // Exit the function if any field in the current tab is invalid:
   if (n == 1 && !validateForm()) return false;
  // Hide the current tab:
  x[currentTab].style.display = "none";
  // Increase or decrease the current tab by 1:
  currentTab = currentTab + n;
  // if you have reached the end of the form...
  if (currentTab >= x.length) {
    // ... the form gets submitted:
    document.getElementById("regForm").submit();
    // onclick="alert('Form submitted successfully!');"
    return false;
  }
  // Otherwise, display the correct tab:
  showTab(currentTab);
}

function validateForm() {
  // This function deals with validation of the form fields
  var x, y, i, z, q, valid = true;
  x = document.getElementsByClassName("tab");
  y = x[currentTab].getElementsByTagName("input");
  z = x[currentTab].getElementsByTagName("textarea");
  q = x[currentTab].getElementsByTagName("select");
  // A loop that checks every input field in the current tab:
  for (i = 0; i < y.length; i++) {
    // If a field is empty...
    if (y[i].value == "" && y[i].required) {
      // add an "invalid" class to the field:
     ...