body {
    font-family: Arial, sans-serif;
    color: #fff;
    background-color: #000;
    margin: 0;
    padding: 0;
    overflow-x: hidden;
    display: flex;
    min-height: 100vh;
    flex-direction: column;
}

body.light {
    color: #000;
    background-color: #fff;
}

body.yellow {
    background-color: #fffbea;
    color: #000;
}

.background-image {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('img/fons/index.jpg') no-repeat center center fixed;
    background-size: cover;
    z-index: -1;
}

.top-footer, .bottom-footer {
    display: flex;
    justify-content: space-between;
    padding: 10px 20px;
    background-color: rgba(0, 0, 0, 0.8);
    transition: background-color 0.5s ease;
}

.top-footer.light, .bottom-footer.light {
    background-color: rgba(255, 255, 255, 0.8);
}

.top-footer.yellow, .bottom-footer.yellow {
    background-color: #ffd700;
}

button {
    padding: 10px;
    border: none;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.3s ease;
    color: #000;
    background-color: #ffd700;
    border-radius: 4px;
    display: inline-block;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

button:hover {
    background-color: #ffdc73;
    transform: scale(1.05);
}

a {
    color: inherit;
    text-decoration: none;
    margin: 0 10px;
}

a:hover {
    text-decoration: underline;
}

main, .left-column, .right-column {
    margin: 20px;
}

.left-column, .right-column {
    flex: 1;
}

.central-header {
    flex: 2;
    text-align: center;
}

.container {
    display: flex;
    flex: 1;
    width: 100%;
}

#popup-message {
    animation: fade-out 0.5s ease-out 30s forwards;
}

@keyframes fade-out {
    to {
        opacity: 0;
        visibility: hidden;
    }
}