html, body {
    height: 100%;
    margin: 0; padding: 0;
    background-image: url('img/background.jpg');
    background-position: center center;
    background-repeat: no-repeat;
    background-size: cover;
    background-attachment: fixed;
    font-family: Arial, sans-serif;
    color: #fff;
    min-height: 100vh;
}

.page-wrapper {
    display: flex;
    max-width: 1100px;
    margin: 40px auto;
    gap: 30px;
    height: 80vh;             /* hauteur fixe pour pouvoir centrer */
    align-items: center;      /* centrage vertical */
    justify-content: center;  /* centrer horizontalement contenu */
    box-sizing: border-box;
}

.registration-box {
    width: 600px;
    padding: 30px 25px;
    background-color: #1a1a1a;
    border: 2px solid #00b0f2;
    border-radius: 8px;
    box-sizing: border-box;
}

.sidebar {
    flex: 0 0 350px;
    background-color: #222;
    padding: 20px;
    border-radius: 8px;
    box-sizing: border-box;
    max-height: 80vh;
    overflow-y: auto;
    align-self: flex-start; /* sidebar alignée en haut */
}

/* Responsive : ajout du pile vertical en écran étroit */

@media (max-width: 900px) {
    .page-wrapper {
        flex-direction: column;
        height: auto;
        max-width: 90%;
        margin: 20px auto;
        align-items: center;
    }
    .registration-box {
        width: 100%;
        max-width: 600px;
        padding: 20px 15px;
    }
    .sidebar {
        width: 100%;
        max-height: none;
        overflow: visible;
        margin-top: 30px;
        align-self: center;
    }
}