JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Maddy's Cubicle</title>
    <link href="https://fonts.googleapis.com/css2?family=Baloo+Paaji+2&display=swap" rel="stylesheet">
    <link rel="stylesheet" href="./style.css">
</head>
<body>
    <navbar>
        <h1 class="brand_name">Maddy's Cubicle</h1>
        <ul type="none" class="nav">
            <li><a href="#showcase">Home</a></li>
            <li><a href="#course_content">Courses</a></li>
            <li><a href="#join_us">Join Us</a></li>
        </ul>
    </navbar>

    <section id="showcase">       
        <div id="moto">
            We are Here For You!
        </div>
    </section>

    <div id="course_content">
        <h2>Courses We Provide!</h2>
        <iframe width="300" height="200" src="https://www.youtube.com/embed/fBNz5xF-Kx4" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
        <iframe width="300" height="200" src="https://www.youtube.com/embed/sBws8MSXN7A" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
        <iframe width="300" height="200" src="https://www.youtube.com/embed/e1IyzVyrLSU" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
    </div>

    <div id="join_us">
        <h1>Join Us! </h1>
        <form action="">
            <label for="name">Name</label>
            <input type="text"  id="name"><br>
            
            <label for="education">Highest Education Pursued</label>
            <select  id="education">
                <option>High School</option>
                <option>Under Grad</option>
                <option>Post Grad</option>
                <option>Master Degree</option>
            </select>
            <br>
            
           ...

CSS

*
{
    background-color: #010a43;
    color: #ffffff;
    margin:0;
    padding:0;
    font-family: 'Baloo Paaji 2', cursive;
}
navbar
{
    position: fixed;
    top: 0;
    width: 100%;
    overflow: hidden;
    padding-top: 10px;
    z-index: 3;
}
.brand_name
{
    margin: 40px 50px;
    display: inline;
}
.nav
{
    padding-top: 40px;
    display:inline;
    float: right;
}
.nav li
{
    margin-top: 20px;
    display:inline;
    
    
}
.nav li a
{
    text-decoration: none;
    font-size: 1.2em;
    padding: 5px 10px;
}
.nav li a:hover
{
    background-color:#00bcd4 ;
}
@media only screen and (max-width: 600px)
{
    .brand_name
    {
        margin:0;
        text-align: center;
        display: block;
    }
    .nav
    {
        margin: 0;
        padding: 0;;
        text-align: center;
        display: block;
        overflow: hidden;
        float: none;
    }   
    .nav li 
    {
        padding: 0;
        margin: 0;
        overflow: hidden;
    } 
    
}
/* navbar done */

/* showcase starts */
#showcase
{
    height: 350px;
    width: 100%;
    display: block;
    background-image: url("https://www.seekpng.com/png/detail/488-4883566_web-and-technology-background-svg-black-and-white.png");
    /* background: url('../media/g2.jpg'); */
    background-repeat: no-repeat;
    background-size: cover;
    background-position: center;

}
#moto
{

    position: relative;
    top: 280px;
    color: black;
    font-size: 2rem;
    background-color: transparent;
    float: right;
    margin-right: 10%;
    
}
/* showcase ends  */

/* course content start */
#course_content
{
    padding: 20px 20px;
    margin: 20px 20px;
    text-align: center;
}
#course_content iframe
{
    margin: 20px 20px;
}
#course_content h2
{
    text-align: center;
    font-size: 2em;
}
/* course content end  */
/* join us start  */
#join_us
{
    width: 80%;
    margin: 10px 10%;
}
#join_us h1
{
    text-align: center;
}
#join_us label
{
    display: inline-block;
    width: 200px;
...