body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    display: flexbox;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    background-color: #f0f0f0;
}

header {
    background-color: #010201b6;
    color: rgb(255, 255, 255);
    padding: 20px;
    text-align: center;
    width: 100%;
}

main {
    text-align: center;
}

button {
    background-color: #9b99999c;
    color: #ffffff;
    width: 10em;
    height: 5em;
    border: none;
    cursor: pointer;
    font-size: 26px;
    border-radius: 50px;
    overflow: hidden;
    z-index: -1;
    box-shadow: 6px 6px 12px #000000,
    -6px -6px 12px #fc0000;
}
button::before{
    content: '';
    width: 0;
    height: 3em;
    top: 0;
    left: 0;
    background-image: linear-gradient(to right,rgb(0, 245, 0) 0%, rgb(7, 1, 1) 100%);
    transition: 1s ease;
    display: block;
    z-index: -1;
}

button:hover::before {
    width: 10em;
    
}
nav{
    padding: 1rem;
    background: #000000;
}
nav ul{
    list-style-type: none;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: space-around;
}

nav li a{
    color: #f0f0f0;
    text-decoration: none;
    margin: 10%;
}
nav li a:hover{
    color: #fc0000;
    
    text-shadow: 0 0 15px #01fefe;
}
nav li a::after{
    content: '';
    bottom: -25px;
    height: 0px;
    width: 10px;
    left: 50%;
    position: absolute;
    background-color: #01fefe;
    border-radius: 50%;
    transition: all 300ms;
}
nav li a:hover::after{
    height: 10px;
    left: 50%;
}