body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-family:'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif;
    background-color: #2c3e50; /* Fondo oscuro */
    color: #ecf0f1;
}

nav {
    background-color: #00bfff;
    overflow: hidden;
}

nav ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
}

nav ul li {
    float: left;
}

nav ul li a {
    display: block;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

nav ul li a:hover {
    background-color: #ff4d4d;
}

.container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    width: 90%;
    max-width: 600px;
}

button {
    padding: 10px 20px;
    font-size: 16px;
    background-color: #000000;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s;
    margin: 5px;
    width: calc(100% - 10px);
    box-sizing: border-box;
}

button:hover {
    background-color: #444444;
}

#cardContainer {
    margin-top: 20px;
    width: 100%;
    display: flex;
    justify-content: center;
    border-radius: 20px 0px 0px 20px;
}

#card {
    display: flex;
    width: 100%;
    height: 150px;
    border: 2px solid #333;
    background-color: #ffffff;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
    transition: transform 0.6s ease-in-out, box-shadow 0.3s;
    box-sizing: border-box;
}

.card-half {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2em;
    font-family:'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif;
    text-transform:uppercase;
    color: white;
    padding: 10px;
    box-sizing: border-box;
}

#theme1Container {
    background-color: #ff4d4d;
    border-right: 1px solid #333;
}

#theme2Container {
    background-color: #4da6ff;
}

.hidden {
    visibility: hidden;
}

.visible {
    visibility: visible;
}

.spin {
    animation: spin 0.6s ease-in-out;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

footer {
    text-align: center;
    padding: 10px 0;
    background-color: #333;
    color: #fff;
    width: 100%;
    position: fixed;
    bottom: 0;
}

#fullscreenButton {
    position: fixed;
    bottom: 10px;
    right: 10px;
    background-color: #27ae60;
}

#fullscreenButton:hover {
    background-color: #229954;
}