* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    font-family:'Franklin Gothic Medium', 'Arial Narrow', Arial, sans-serif;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #373737;
    flex-direction: column;
}

h3 {
    position: relative;
    font-size: 20px;
    color: #f9f9f9;
    letter-spacing: 1px;
    font-weight: 500;
    margin-bottom: 8px;
}

#form {
    position: relative;
}

#form #email {
    width: 300px;
    background-color: #292929;
    outline: none;
    border: none;
    padding: 10px;
    color: #fff;
    font-size: 18px;
}

#form .inputbox {
    position: relative;
}

#text {
    display: block;
    color: #000;
    font-weight: 500;
    padding: 5px;
}

#form.invalid .inputbox::before {
    content: "";
    position: absolute;
    right: 12px;
    top: 8px;
    width: 24px;
    height: 24px;
    background: url(invalid.png);
    background-size: cover;
    z-index: 1000;
}

#form.valid .inputbox::after {
    content: "";
    position: absolute;
    right: 12px;
    top: 8px;
    width: 24px;
    height: 24px;
    background: url(valid.png);
    background-size: cover;
    z-index: 1000;
}