I want to make vertically space-between those two pictures at right side. Can you help me with that? Should change my HTML struct or something? I couldn't find a solution with this HTML struct. s
<!DOCTYPE html>
<html>
<head>
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.0/dist/css/bootstrap.min.css" integrity="sha384-B0vP5xmATw1+K9KRQjQERJvTumQW0nPEzvF6L/Z6nronJ3oUOFUFpCjEUQouq2+l" crossorigin="anonymous">
    <link rel="stylesheet" href="./style.css">
</head>
<body>
    <div class="container mt-5 border">
        <div class="row">
            <div class="col-md-6">
                <img class="img-fluid a" src="https://images.unsplash.com/photo-1623709537069-80ff1bfff9e7?ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&ixlib">
            </div>
            <div class="col-md-6">
                <div class="row ">
                    <div class="col-12 mt-md-6">
                        <img class="img-fluid b" src="https://images.unsplash.com/photo-1623709537069-80ff1bfff9e7?ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&ixlib">
                    </div>
                    <div class="col-12 mt-md-6">
                        <img class="img-fluid c" src="https://images.unsplash.com/photo-1623709537069-80ff1bfff9e7?ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&ixlib">
                    </div>
                </div>
            </div>
        </div>
    </div>
</body>
</html>
img {
    object-fit: cover;
    border: 1px solid red;
}
.a {
    width: 100%;
    height: 500px;
}
.b,
.c {
    width: 100%;
    height: 200px;
}
@media (max-width: 768px) {
    .a {
        height: 200px;
    }
    .b,
    .c {
        margin-top: 1rem;
    }
}
 
     
    