body { font-family: Arial; margin:0; }

header, footer {
    background:#333;
    color:white;
    text-align:center;
    padding:15px;
}

nav {
    background:#555;
    padding:10px;
    text-align:center;
}

nav a {
    color:white;
    margin:5px;
    padding:8px;
    background:#777;
    text-decoration:none;
    border-radius:5px;
    display:inline-block;
}

section {
    padding:20px;
    border-bottom:1px solid #ccc;
}

.caja {
    width:100px;
    height:100px;
    background:blue;
    margin-top:10px;
}
main {
    display: grid;
    grid-template-columns: repeat(3, 1fr); /* 3 cards por fila */
    gap: 15px;
    padding: 20px;
}

section {
    background: white;
    border-radius: 8px;
    padding: 15px;
    border: none; 
    box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}

section:hover {
    transform: scale(1.02);
    transition: 0.2s;
}

button {
    background: #333;
    color: white;
    border: none;
    padding: 8px 10px;
    border-radius: 5px;
    cursor: pointer;
    margin-top: 10px;
}

button:hover {
    background: #555;
}