A Simple Quiz with PHP and Ajax with Radio Buttons and multiple form input steps

HTML

<div class="container container-main">
<div class="row justify-content-center">
<div class="form-container">
<form id="demoForm">
<ul id="progress_steps" class="d-flex justify-content-center">
<li class="active" id="step_1"></li>
<li id="step_2"></li>
<li id="step_3"></li>
<li id="step_4"></li>
<li id="step_5"></li>
</ul>

<fieldset>
<div class="fieldset-content-container">
<div class="row g-3 justify-content-between">
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-info">
<h4>1. Which country has the most earthquakes?</h4>
<div class="input-error-check"></div>
</div>

</div>
</div>
</div>
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-input">

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-01" id="question-01-A" value="A" />
<label for="question-01-A" class="radio-item-label"><span>Japan</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-01" id="question-01-B" value="B" />
<label for="question-01-B" class="radio-item-label"><span>Australia</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-01" id="question-01-C" value="C" />
<label for="question-01-C" class="radio-item-label"><span>USA</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-01" id="question-01-D" value="D" />
<label for="question-01-D" class="radio-item-label"><span>Italy</span></label>
</div>

</div>

</div>
</div>
</div>
</div> 
</div> 
<p class="quiz-sub"></p>
<button type="button" class="btn btn-secondary form-button-next next-step"><span class="form-button-next-label"><i class="fa-solid fa-circle-arrow-right"></i></span>NEXT</button> 
</fieldset>

<fieldset>
<div class="fieldset-content-container">
<div class="row g-3 justify-content-between">
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-info">
<h4>2. Which country has the most islands?</h4>
<div class="input-error-check"></div>
</div>

</div>
</div>
</div>
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-input">

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-02" id="question-02-A" value="A" />
<label for="question-02-A" class="radio-item-label"><span>USA</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-02" id="question-02-B" value="B" />
<label for="question-02-B" class="radio-item-label"><span>Sweden</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-02" id="question-02-C" value="C" />
<label for="question-02-C" class="radio-item-label"><span>Albania</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-02" id="question-02-D" value="D" />
<label for="question-02-D" class="radio-item-label"><span>Germany</span></label>
</div>

</div>

</div>
</div>
</div>
</div> 
</div> 
<p class="quiz-sub"></p>
<button type="button" class="btn btn-secondary form-button-previous previous-step"><span class="form-button-previous-label"><i class="fa-solid fa-circle-arrow-left"></i></span>PREVIOUS</button> 
<button type="button" class="btn btn-secondary form-button-next next-step"><span class="form-button-next-label"><i class="fa-solid fa-circle-arrow-right"></i></span>NEXT</button> 
</fieldset>

<fieldset>
<div class="fieldset-content-container">
<div class="row g-3 justify-content-between">
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-info">
<h4>3. Which country has the most lawyers per capita?</h4>
<div class="input-error-check"></div>
</div>

</div>
</div>
</div>
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-input">

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-03" id="question-03-A" value="A" />
<label for="question-03-A" class="radio-item-label"><span>Belgium</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-03" id="question-03-B" value="B" />
<label for="question-03-B" class="radio-item-label"><span>North Korea</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-03" id="question-03-C" value="C" />
<label for="question-03-C" class="radio-item-label"><span>South Korea</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-03" id="question-03-D" value="D" />
<label for="question-03-D" class="radio-item-label"><span>USA</span></label>
</div>

</div>

</div>
</div>
</div>
</div> 
</div> 
<p class="quiz-sub"></p>
<button type="button" class="btn btn-secondary form-button-previous previous-step"><span class="form-button-previous-label"><i class="fa-solid fa-circle-arrow-left"></i></span>PREVIOUS</button> 
<button type="button" class="btn btn-secondary form-button-next next-step"><span class="form-button-next-label"><i class="fa-solid fa-circle-arrow-right"></i></span>NEXT</button> 
</fieldset>

<fieldset>
<div class="fieldset-content-container">
<div class="row g-3 justify-content-between">
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-info">
<h4>4. Which country has the most fresh water?</h4>
<div class="input-error-check"></div>
</div>

</div>
</div>
</div>
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-input">

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-04" id="question-04-A" value="A" />
<label for="question-04-A" class="radio-item-label"><span>Italy</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-04" id="question-04-B" value="B" />
<label for="question-04-B" class="radio-item-label"><span>The Netherlands</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-04" id="question-04-C" value="C" />
<label for="question-04-C" class="radio-item-label"><span>USA</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-04" id="question-04-D" value="D" />
<label for="question-04-D" class="radio-item-label"><span>Brazil</span></label>
</div>

</div>

</div>
</div>
</div>
</div> 
</div> 
<p class="quiz-sub"></p>
<button type="button" class="btn btn-secondary form-button-previous previous-step"><span class="form-button-previous-label"><i class="fa-solid fa-circle-arrow-left"></i></span>PREVIOUS</button> 
<button type="button" class="btn btn-secondary form-button-next next-step"><span class="form-button-next-label"><i class="fa-solid fa-circle-arrow-right"></i></span>NEXT</button> 
</fieldset>


<fieldset>
<div class="fieldset-content-container">
<div class="row g-3 justify-content-between">
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-info">
<h4>5. Which Country has the most pollution?</h4>
<div class="input-error-check"></div>
</div>

</div>
</div>
</div>
<div class="col-md-6">
<div class="card h-100">
<div class="card-body">

<div class="quiz-question-input">

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-05" id="question-05-A" value="A" />
<label for="question-05-A" class="radio-item-label"><span>Mongolia</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-05" id="question-05-B" value="B" />
<label for="question-05-B" class="radio-item-label"><span>China</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-05" id="question-05-C" value="C" />
<label for="question-05-C" class="radio-item-label"><span>India</span></label>
</div>

<div class="form-check">
<input type="radio" class="form-check-input radio-item" name="question-05" id="question-05-D" value="D" />
<label for="question-05-D" class="radio-item-label"><span>Belgium</span></label>
</div>

</div>

</div>
</div>
</div>
</div> 
</div> 
<p class="quiz-sub"></p>
<button type="button" class="btn btn-secondary form-button-previous previous-step"><span class="form-button-previous-label"><i class="fa-solid fa-circle-arrow-left"></i></span>PREVIOUS</button> 
<button id="btnLast" type="button" class="btn btn-secondary form-button-next next-step"><span class="form-button-next-label"><i class="fa-solid fa-circle-arrow-right"></i></span>NEXT</button> 
</fieldset>

<fieldset>

<div class="quiz-message-container">
<div id="quizMessage"></div>
</div>

<p class="quiz-sub"></p>
<button id="btnBack" type="button" class="btn btn-secondary form-button-previous previous-step"><span class="form-button-previous-label"><i class="fa-solid fa-circle-arrow-left"></i></span>BACK</button>
<button type="button" class="btn btn-success form-button-submit next-step" id="buttonSubmit" ><span class="form-button-submit-label"><i class="fa-solid fa-share-from-square"></i></span>SUBMIT</button> 
</fieldset>

</form>

<div id="progress-container">
<div class="progress">
<div class="progress-bar" role="progressbar" aria-valuemin="0" aria-valuemax="100"></div>
</div>
</div>

</div>
</div>

CSS

.radio-item {
position: relative;
top: 5px;
}	

.radio-item-label {
cursor: pointer;
}

.radio-item-label span {
padding: 4px 10px;
border: 1px solid #eee;
display: inline-block;
width: 210px;
color: rgba(0, 155, 162, 0.92);          
border-radius: 4px;
}

.radio-item-label span:hover {
background-color: rgba(0, 155, 162, 0.22);
}

.container-main {
margin: 1em auto;
max-width: 640px;
padding: 2rem 2rem 0 2rem;
border: 1px solid rgba(100, 100, 100, 0.24);
background-color: rgba(255, 255, 255, 0.44);
}

.demo-section .card-text {
padding: 20px;
}

.container-main .button-container  {
text-align: right;
}

.container-main .submit-button {
width: 100%;
text-align: center;
padding: 4px 20px;
}

.container-main .message-container {
background-color: rgba(255, 118, 0, 0.20);
border-radius: 4px;
text-align: center;
padding: 4px 20px;
}

.container-main label {
border-bottom: none !important;
}	

.container-main input:checked+label {
border-bottom: none !important;
}

.quiz-question-container {

}

.quiz-question-container .card {

}

.quiz-question-info {
padding: 1rem;
font-size: larger;
text-align: center;
}	

.quiz-question-info h4 {
font-size: 1em;
margin: 2rem 1rem 1rem 1rem;
}

.quiz-sub {
margin-bottom: 1rem;
}	

.quiz-question-input {
padding: 1rem;
}	

.quiz-buttons-container {
margin-top: 1rem;
}

#demoForm fieldset:not(:first-of-type) {
display: none
}

#progress_steps {
margin-bottom: 30px;
margin-right: 40px;
overflow: hidden;
text-align: center;
color: #9A9A9A;
}

#progress_steps .active {
color: #2F8D46;
}

#progress_steps li {
list-style-type: none;
font-size: 15px;
width: 10%;
float: left;
position: relative;
z-index: 2;
font-weight: 400;
}

#progress_steps #step_1:before {
content: "1";
}

#progress_steps #step_2:before {
content: "2";
}

#progress_steps #step_3:before {
content: "3";
}

#progress_steps #step_4:before {
content: "4";
}

#progress_steps #step_5:before {
content: "5";
}

#progress_steps #step_6:before {
content: "6";
}

#progress_steps #step_7:before {
content: "7";
}

#progress_steps #step_8:before {
content: "8";
}

#progress_steps #step_9:before {
content: "9";
}

#progress_steps li:before {
width: 24px;
height: 24px;
line-height: 20px;
display: block;
font-size: 14px;
color: #ffffff;
background: lightgray;
border-radius: 50%;
margin: 0 auto 5px auto;
padding: 2px;
}

#progress_steps li:after {
content: '';
width: 100%;
height: 2px;
background: lightgray;
position: absolute;
left: 0;
top: 12px;
z-index: -1;
}

#progress_steps li.active:before,
#progress_steps li.active:after {
background: #61677C;
}

#progress-container {
margin-top: 1rem;
}

.progress {
height: 4px;
margin: 0;
border-radius: 0 !important;
font-size: 11px;
letter-spacing: 1px;
}

.progress-bar {
background-color: #b9b9bd;
}

.input-info {
padding: 1em;
background-color: rgba(71, 70, 70, 0.10);
border-radius: 10px;
text-align: center;
margin-bottom: 2rem;
}

.previous-step {
float: left;
}

.next-step {
float: right;
}

.input-container {
margin: 2em 0;
}

.form-input-text {
width: 100%;
}

.error-message-input-container {
height: 40px;
padding-top: 10px;
}

.error-message-input-content {
margin-top: 1rem;
font-size: 11px;
color: #FF0004;
padding: 0 32px;
position: relative;
text-align: center;
}

.error-message-input-content::before {
position: absolute;
font-family: 'FontAwesome';
top: 0;
left: 0;
content: "\f071";
}

.error-message-input-content::after {
position: absolute;
font-family: 'FontAwesome';
top: 0;
right: 0;
color: rgba(0, 155, 162, 0.92);
content: "\f192";
}

.input-error-state {
background-color: rgba(255, 132, 134, 0.1);
}

.form-container {
max-width: 600px;
}

.form-container .input-container {
margin: 0 auto;
max-width: 190px;
}

.form-container .form-button-next {
position: relative;
width: 129px;
padding: 4px 6px 4px 12px;
text-align: left;
}

.form-container .form-button-next-label {
position: absolute;
top: 0;
right: 0;
display: inline-block;
padding: 4px 6px;
background: rgba(0, 0, 0, 0.15);
border-radius: 0 3px 3px 0;
}

.form-container .form-button-previous {
position: relative;
width: 129px;
padding: 4px 6px 4px 40px;
text-align: left;
}

.form-container .form-button-previous-label {
position: absolute;
top: 0;
left: 0;
display: inline-block;
padding: 4px 6px;
background: rgba(0, 0, 0, 0.15);
border-radius: 3px 0 0 3px;
}

.form-container .form-button-submit {
position: relative;
width: 129px;
padding: 4px 6px 4px 12px;
text-align: left;
}

.form-container .form-button-submit-label {
position: absolute;
top: 0;
right: 0;
display: inline-block;
padding: 4px 6px;
background: rgba(0, 0, 0, 0.15);
border-radius: 0 3px 3px 0;
}

.form-container .button-next {
float: right;
}

.form-container .button-previous {
float: left;
}

.form-container .button-submit {
float: right;
}

.quiz-message-container {
margin-bottom: 2rem;
padding: 3rem 1rem 1rem 1rem;
text-align: center;
border-radius: 6px;
background-color: rgba(0, 155, 162, 0.2);
border: 1px solid rgba(0, 155, 162, 0.12);
min-height: 180px;
}

.quiz-message-container p {
margin: 0;
}


$(document).ready(function() {

var currentMsfStep, nextMsfStep, previousMsfStep;
var opacity;
var current = 1;
var steps = $("fieldset").length;

setProgressSteps(current);

$(".next-step").click(function() {
if ($('input[type=radio]:checked:visible').length == 0) {
$('.input-error-check:visible').html('<div class="error-message-input-content">Please select an answer</div>');
return false;
}

currentMsfStep = $(this).parent();
nextMsfStep = $(this).parent().next();
$("#progress_steps li").eq($("fieldset")
.index(nextMsfStep)).addClass("active");
nextMsfStep.show();
currentMsfStep.animate({
opacity: 0
}, {
step: function(now) {
opacity = 1 - now;
currentMsfStep.css({
'display': 'none',
'position': 'relative'
});
nextMsfStep.css({
'opacity': opacity
});
},
duration: 500
});
setProgressSteps(++current);
});

$(".previous-step").click(function() {
currentMsfStep = $(this).parent();
previousMsfStep = $(this).parent().prev();
$("#progress_steps li").eq($("fieldset")
.index(currentMsfStep)).removeClass("active");

previousMsfStep.show();
currentMsfStep.animate({
opacity: 0
}, {
step: function(now) {
opacity = 1 - now;
currentMsfStep.css({
'display': 'none',
'position': 'relative'
});
previousMsfStep.css({
'opacity': opacity
});
},
duration: 500
});
setProgressSteps(--current);
});

function setProgressSteps(currentStep) {
var percent = parseFloat(100 / steps) * current;
percent = percent.toFixed();
$(".progress-bar").css("width", percent + "%");
$('.input-error-check').html('');
$('input[type=text]').removeClass('input-error-state');
}

$("#buttonSubmit").click(function(event) {
$.ajax({
type: 'post',
url: 'post.php',
data: $('#demoForm').serialize(),
success: function (data) {
$("#quizMessage").html(data);
$("#buttonSubmit").prop('disabled', true);
}
});
event.preventDefault();
}); 

$("#btnLast").click(function () {
$("#quizMessage").html("Are you SURE you have answered all the questions correctly?");
});

$("#btnBack").click(function () {
$("#buttonSubmit").prop('disabled', false);
$("#quizMessage").html("");
});

});

PHP post

<?php

$answer_01 = $_POST['question-01'];
$answer_02 = $_POST['question-02'];
$answer_03 = $_POST['question-03'];
$answer_04 = $_POST['question-04'];
$answer_05 = $_POST['question-05'];

$totalRight = 0;

if ($answer_01 == "A") { $totalRight++; }
if ($answer_02 == "B") { $totalRight++; }
if ($answer_03 == "C") { $totalRight++; }
if ($answer_04 == "D") { $totalRight++; }
if ($answer_05 == "A") { $totalRight++; }

// result:

if ($totalRight == 0 ) {
$result = '<p><strong>All</strong> answers are <strong>incorrent</strong></p>
<p>GO BACK AND TRY AGAIN</p>';
}

if ($totalRight == 1 ) {
$result = '<p>Only <strong>one</strong> answer is <strong>correct</strong></p>
<p>GO BACK AND TRY AGAIN</p>';
}

if ($totalRight == 2 ) {
$result = '<p><strong>Two</strong> answers are <strong>correct</strong></p>
<p>GO BACK AND TRY AGAIN</p>';
}

if ($totalRight == 3 ) {
$result = '<p><strong>Three</strong> answers are <strong>correct</strong></p>
<p>GO BACK AND TRY AGAIN</p>';
}

if ($totalRight == 4 ) {
$result = '<p><strong>Four</strong> answers are <strong>correct</strong></p>
<p>GO BACK AND TRY AGAIN</p>';
}

if ($totalRight == 5 ) {
$result = '<p><strong>All</strong> answers are <strong>correct</strong></p>
<p>WELL DONE!</p>';
}

echo '' . $result . ''; 

?>