Option box not appearing below the box

Is there any reason why this is happening?the option box is not appearing below the box itself

The option appears normally on big screen, it’s just when I inspect and make it responsive it seems like the option box is not moving at all? are there any particular details why?

I am a new developer and would like to know more on how to prevent this happening, and if someone please tell me why it’s happening too? thank you

html code:

    <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <!-- meta name/property starts -->
    <meta name="description" content="CDA offers driving lessons in Cambridge and surrounding areas extending all through Cambridgeshire. CDA has a fully-qualified team of instructors ">
    <meta property="og:title" content="Driving Lessons Cambridge | CDA">
    <meta property="og:description" content="CDA offers driving lessons in Cambridge and surrounding areas extending all through Cambridgeshire. CDA has a fully-qualified team of instructors ">
    <meta property="og:url" content="https://www.cambridgedrivingacademy.com">
    <meta property="og:site_name" content="cambridge driving ac">
    <meta property="og:type" content="website">
    <meta name="google-site-verification" content="-U4J2qSZr6SaN8sIfVFsM1Kl280vQ5CifW_lt12tbeo">
    <meta name="twitter:title" content="Driving Lessons Cambridge | CDA">
    <meta name="twitter:description" content="CDA offers driving lessons in Cambridge and surrounding areas extending all through Cambridgeshire. CDA has a fully-qualified team of instructors ">
    <!-- meta name close -->
    <title>CDA | Cambridge Driving Academy | Driving School in Cambridge</title>
    <!-- fas cdn -->
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.1.1/css/all.min.css">
    <!-- personal css -->
    <link rel="stylesheet" href="/css/style.css" text="css">
    <link rel="stylesheet" href="/css/gallery.css" text="css">
    <!-- custom css -->
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/aos/2.3.4/aos.css">
    <link rel="stylesheet" href="/css/enrolment.css">
    <!-- swiper -->
    <link  rel="stylesheet"  href="https://unpkg.com/swiper@8/swiper-bundle.min.css" />
    <!-- llight gallery CDN -->
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/lightgallery-js/1.4.0/css/lightgallery.min.css">

</head>
<body>
    
    <!-- header section starts -->
        <header>
            <a href="#" class="logo">Cambridge <span>Driving Academy</span></a>
            <a href="#" ><img src="imgs/CDA_NEWLogo.png" class="img-logo" alt=""></a>
            <div class="navbar">
                <a href="#home">Home</a>
                <a href="index.html#courses">Courses</a>
                <a href="instructors.html">Team</a>
                <a href="index.html#about-us">About Us</a>
                <a href="training.html">Instructor Training</a>
                
                <a href="pricing.html">Prices</a>
            </div>
            <div class="icons">
                <i class="fa-solid fa-bars" id="menu-bars"></i>
                <a href="https://www.instagram.com/cambridgedriving/?hl=en" target="_blank">
                    <i class="fa-brands fa-instagram"></i>
                </a>
                <a href="https://www.facebook.com/cambridgedrivingacademy" target="_blank">
                    <i class="fa-brands fa-facebook">
                    </i></a>
                <a href="tel:07496 842781">
                    <i class="fa-solid fa-phone"></i>
                </a>
                
            </div>
        </header>
    <!-- ender ends -->

    <div class="enrolment-logo">
        <img src="/imgs/CDA_NEWLogo.png" alt="">
    </div>

    <!-- enrolment form starts -->
    <div class="cda-form" id="contact">

        <h1 class="heading">
            <span>Enrolment Form</span>
        </h1>
    
        <div class="row">


            <!-- <div class="image">
                <img src="/imgs/contact.png" alt="contact-us">
            </div> -->

            

 
    
            <form action="contact-form.php" method="POST">
    
                <span>Your Full Name</span>
                <input type="text" required placeholder="Enter your name" id="name" class="box" maxlength="40">
    
                <span>Your Email Address</span>
                <input type="email" required placeholder="Enter your email" id="email" class="box" maxlength="40">

                <span>Your Date of Birth</span>
                <input type="date" required placeholder="Enter your email" id="email" class="box" maxlength="40">

                <span>Your Address</span>
                <input type="text" required placeholder="First Line Address" id="email" class="box" maxlength="40">
                <input type="text"  placeholder="Second Line Address" id="email" class="box" maxlength="40">
                <input type="text"  placeholder="Third Line Adress" id="email" class="box" maxlength="40">
    
                <span>Your mobile number</span>
                <input type="text" required placeholder="Enter your mobile number" id="number" 
                class="box" maxlength="99999999999" onkeypress="if(this.value.length == 10) return false;">
    
                <span>Transmission Type </span>
                <select name="Courses" id="courses" class="box" required>
                    <option value="" disabled selected> Select Transmission --</option>
                    <option value="Manual Driving Course">Manual</option>
                    <option value="Automatic Driving Course">Automatic</option>
                </select>

                <span>Licence Type </span>
                <select name="Courses" id="courses" class="box" required>
                    <option value="" disabled selected> What type of licence do you have?</option>
                    <option value="Manual Driving Course">Provisional Licence</option>
                    <option value="Automatic Driving Course">
                        Full Automatic Licence</option>
                    <option value="Manual Driving Course">Full Licence</option>
                    <option value="Manual Driving Course">Foreign Licence</option>
                </select>

                <span>Your Driving Licence Number</span>
                <input type="email" required placeholder="Enter your Driving Licence Number" id="email" class="box" maxlength="40">
                
                <span>Theory Test </span>
                <select name="Courses" id="courses" class="box" required>
                    <option value="" disabled selected>Pass or Failed</option>
                    <option value="Manual Driving Course">Passed</option>
                    <option value="Automatic Driving Course">Failed</option>
                    <option value="Automatic Driving Course">Not Taken</option>
                </select>

                <span>Practical Test </span>
                <select name="Courses" id="courses" class="box" required>
                    <option value="" disabled selected>Pass or Failed</option>
                    <option value="Manual Driving Course">Passed</option>
                    <option value="Automatic Driving Course">Failed</option>
                    <option value="Automatic Driving Course">Not Taken</option>
                </select>

                <span>If you have an upcoming Theory and/or Practical Driving Test, please select one of the option </span>
                <select name="Courses" id="courses" class="box" required>
                    <option value="" disabled selected>Test booked --</option>
                    <option value="Manual Driving Course">Theory Test</option>
                    <option value="Automatic Driving Course">Driving Test</option>
                    <option value="Automatic Driving Course">Nothing Booked at the moment</option>
                </select>

                <Span>If you have already your Practical Driving Test booked, please provide booking reference number, test date, time and test centre:<Span>
                    <textarea name="message" id="message" cols="30" rows="3" placeholder="Type of test, Booking Ref #, Test Date, Time and Test Centre"></textarea>

                <Span>Driving Experience<Span>
                <textarea name="message" id="message" cols="30" rows="7" placeholder="Additional Information"></textarea>

            

                <h1 class="heading">
                    Parent/s or Guardian/s
                </h1>

                <span>Parents or Guardian's name</span>
                <input type="text" required placeholder="Enter your name, enter N/A if not applicable" id="name" class="box" maxlength="40">

                <span>Parents or Guardian's Email Address</span>
                <input type="text" required placeholder="Enter your guardian's email address, enter N/A if not applicable" id="name" class="box" maxlength="40">

                <span>Parents or Guardian's Contact Phone Number</span>
                <input type="text" required placeholder="Enter your guardian's contact number, enter N/A if not applicable" id="name" class="box" maxlength="40">


                
    
                <input type="submit" value="Submit Form" class="btn">
            </form>



        </div>
    
    </div>
    



    <!-- enrolment form ends -->
    




    <!-- scripts -->
        <script src="https://unpkg.com/swiper@8/swiper-bundle.min.js"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/lightgallery-js/1.4.0/js/lightgallery.min.js"></script>
        <script src="/js/script.js"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/aos/2.3.4/aos.js"></script>
        

        <script>

            AOS.init({
                duration:800,
                offset:150,
            })

            lightGallery(document.querySelector('.gallery .gallery-container'));

            
        </script>

    <!-- script ends -->
</body>
</html>

css code :

.enrolment-logo img {
    height:8rem;
}

.enrolment-logo {
    text-align: center;
    margin-top:5%;
}

.cda-form {
    background-color: #fff;
    padding:2% 15%;
    text-align: center;
    width:80%;
    margin: 0 auto;
}

.cda-form .heading span {
    color:var(--primary-color);

}

.cda-form .row {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap:1.5rem;
}

.cda-form .row .image{
    flex: 1 1 40rem;
    text-align: center;
}

.cda-form .row .image img {
    width:60%;
}

.cda-form .row form  .box,textarea{

    width:100%;
    margin-top: 1rem;
    margin-bottom: 2rem;
    border-radius: .5rem;
    background-color:white;
    box-shadow: var(--box-shadow);
    font-size: 1.8rem;
    color:var(--black);
    resize: none;
    padding:1.4rem;
    font-family: 'Poppins', sans-serif;
}

.cda-form .row form  {
    flex: 1 1 20rem;

}
.cda-form .row form span {
    color:var(--primary-color);
    font-size: 1.6rem;
}
input,option {
    text-align: center;
}

::-webkit-input-placeholder {
    text-align: center;
 }
 
 :-moz-placeholder { /* Firefox 18- */
    text-align: center;  
 }
 
 ::-moz-placeholder {  /* Firefox 19+ */
    text-align: center;  
 }
 
 :-ms-input-placeholder {  
    text-align: center; 
 }


 @media(max-width:1400px){

    .enrolment-logo {
        text-align: center;
        margin-top:10%;
    }
    

}

@media(max-width:850px){

    .enrolment-logo {
        text-align: center;
        margin-top:20%;
    }
    .cda-form .heading span{
        font-size: 5rem;
    }

    .cda-form .row form  .box,textarea{

        font-size:1.5rem;
    }

}

@media(max-width:450px){

    .cda-form .heading span{
        font-size: 5rem;
        text-align: center;
        justify-content: center;
        display: flex;
    }
}