Testimonial carousel html css is a bootstrap snipp which made using bootstrap framework and owl carousel. This is easy to use bootstrap snipp. Images used from pexels website.
Whole html/css code
<!doctype html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/OwlCarousel2/2.3.4/assets/owl.carousel.css" />
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/OwlCarousel2/2.3.4/assets/owl.theme.default.css"/>
<script src="https://kit.fontawesome.com/b31e06099e.js" crossorigin="anonymous"></script>
<title>Hello, world!</title>
<style>
@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@300;400;500;700&display=swap');
body {
background-color: #f4f7fc;
font-family: 'Roboto', sans-serif;
letter-spacing: 0.5px;
}
.owl-prev, .owl-next {
position: absolute;
bottom: 60px;
display: block !important;
}
.owl-prev {
right: 94px;
}
.owl-next {
right: 28px;
}
.owl-prev i, .owl-next i {
color: #fff;
background-color: #fdb44b;
padding: 20px 30px;
}
button {
border: none !important;
border-radius: none !important;
outline: none !important;
}
</style>
</head>
<body>
<div class="py-5">
<div class="container">
<div class="row">
<div class="col-lg-10 p-0 m-0 mx-auto testimonials owl-theme owl-carousel shadow-lg p-5 bg-primary">
<div class="d-lg-flex align-items-center text-white bg-primary">
<div class="author-text">
<div class="p-5">
<p class="lead pb-lg-3">"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus luctus eget tellus a rutrum. Aliquam eleifend, sapien ac fringilla tincidunt, nisl tortor aliquet metus."</p>
<h4 class="font-weight-bold">John Deo</h4>
<p class="mb-0">CEO & Founder</p>
</div>
</div>
<div class="author-img"> <img src="https://images.pexels.com/photos/2765557/pexels-photo-2765557.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=900" class="img-fluid"> </div>
</div>
<div class="d-lg-flex align-items-center text-white bg-primary">
<div class="author-text">
<div class="p-5">
<p class="lead pb-lg-3">"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus luctus eget tellus a rutrum. Aliquam eleifend, sapien ac fringilla tincidunt, nisl tortor aliquet metus."</p>
<h4 class="font-weight-bold">John Deo</h4>
<p class="mb-0">CEO & Founder</p>
</div>
</div>
<div class="author-img"> <img src="https://images.pexels.com/photos/1520760/pexels-photo-1520760.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=900" class="img-fluid"> </div>
</div>
<div class="d-lg-flex align-items-center text-white bg-primary">
<div class="author-text">
<div class="p-5">
<p class="lead pb-lg-3">"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus luctus eget tellus a rutrum. Aliquam eleifend, sapien ac fringilla tincidunt, nisl tortor aliquet metus."</p>
<h4 class="font-weight-bold">John Deo</h4>
<p class="mb-0">CEO & Founder</p>
</div>
</div>
<div class="author-img"> <img src="https://images.pexels.com/photos/3279570/pexels-photo-3279570.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=900" class="img-fluid"> </div>
</div>
<div class="d-lg-flex align-items-center text-white bg-primary">
<div class="author-text">
<div class="p-5">
<p class="lead pb-lg-3">"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus luctus eget tellus a rutrum. Aliquam eleifend, sapien ac fringilla tincidunt, nisl tortor aliquet metus."</p>
<h4 class="font-weight-bold">John Deo</h4>
<p class="mb-0">CEO & Founder</p>
</div>
</div>
<div class="author-img"> <img src="https://images.pexels.com/photos/428328/pexels-photo-428328.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=900" class="img-fluid"> </div>
</div>
</div>
</div>
</div>
</div>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/OwlCarousel2/2.3.4/owl.carousel.min.js"></script>
<script>
$(".testimonials").owlCarousel({
items: 1,
margin:0,
nav: true,
navText: ["<i class='fa fa-angle-left'></i>", "<i class='fa fa-angle-right'></i>"]
});
</script>
</body>
</html>
js fiddle example

