.content {
    display: flex;
    flex-direction: column;
    /* align-items: center; */
    justify-content: center;
    padding: 1rem;
    gap: 1rem;
}
.content-hidden {
    display: none !important;
}
.content.center {
    align-items: center;
}

.btn-huge {
    padding: 2rem;
    font-size: 5vmin            
}

header {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 2rem;
    padding: 1rem;
    background-color: red;
    position: sticky;
    top: 0;
    z-index: 3;
}
header > * {
    color: white;
}