style.css

* {
    margin: 0px;
    padding: 0px;
}

body {
    background: linear-gradient(rgba(44, 76, 121, 0.8), rgba(116, 140, 175, 0.5));
    background-attachment: fixed;
    font-family: sans-serif;
}

h1 {
    text-align: center;
    margin-top: 4vh;
    text-transform: uppercase;
}

form {
    width: 60%;
    margin: auto;
    margin-top: 15px;
}

input,
textarea {
    width: 100%;
    background: transparent;
    outline: none;
    border: none;
    border-bottom: 2px solid #3B5171;
    color: #fff;
    font-size: 18px;
    margin-bottom: 16px;
}

::placeholder {
    color: #fff;
    opacity: 1;
}

input[type="submit"] {
    background: #3B5171;
    font-weight: bold;
    letter-spacing: 2px;
    font-size: 20px;
    height: 50px;
    transition: background-color 1s ease-in-out;
}

input[type="submit"]:hover {
    background-color: #2A3C56;
}