styles.css

body, main, form, h1, h2, h3, h4 {
    margin: 0px;
    padding: 0px;
}
header, footer {
    margin: 10px;
    padding: 10px;
    box-sizing: border-box;
    border-radius: 10px;
    background-color: #003333;
    box-shadow: 0px 0px 10px white;
}
h1, h2, h3, h4 {
    width: 100%;
    text-align: center;
    color: white;
}
button, input, h5 {
    margin: 3px;
}
body {
    background-color: #0D4D4D;
}
main {
    display: flex;
    flex-wrap: wrap;
}
footer {
    justify-content: center;
    display: none;
    position: fixed;
    bottom: 0px;
    right: 0px;
    left: 0px;
    margin-bottom: 0px;
}
section {
    margin: 10px;
    padding: 10px;
    box-sizing: border-box;
    width: calc( 33.33% - 20px );
    border-radius: 10px;
    background-color: #003333;
    box-shadow: 0px 0px 10px white;
}
form {
    display: flex;
    justify-content: center;
}
img {
    width: 100%;
}
h3 {
    margin-bottom: 10px;
}
h4 {
    margin-top: 10px;
}
h5 {
    color: white;
}