body {
    font-family: 'Arial', sans-serif;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    min-height: 100vh;
}

header {
    background-color: #3498db;
    color: #fff;
    text-align: center;
    padding: 2em;
}

section {
    padding: 2em;
}

footer {
    background-color: #007aa3;
    color: #fff;
    text-align: center;
    padding: 1em;
    width: 100%;
}

fond {
    position: fixed;
    top: 0;
    left: 0;
    z-index: 10;
    width: 100vw;
    height: 100vh;
    background-color: rgba(0, 0, 0, 0.4);
    display: flex;
    align-items: center;
    justify-content: center;
}

centre {
    width: 400px;
    height: 400px;
    background-color: #2b303b;
}