* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    color: #333;
}

header {
    background-color: #333;
    color: #fff;
    padding: 20px;
    text-align: center;
}

main {
    width: 100%;
    max-width: 400px;
    padding: 20px;
}

nav {
    background-color: #444;
    padding: 10px;
}

nav a {
    color: #fff;
    text-decoration: none;
    margin: 0 10px;
}

form {
    background: rgba(255, 255, 255, 0.9);
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
}

b {
    display: block;
    margin-bottom: 10px;
    font-size: 1.2em;
    color: #333;
}

.formulariocaja {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
}

input.entradatexto {
    width: 100%;
    padding: 10px;
    margin-bottom: 20px;
    border: 1px solid #ccc;
    border-radius: 5px;
    font-size: 1em;
}

button.botonenviar {
    width: 100%;
    padding: 10px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 1em;
    cursor: pointer;
}

button.botonenviar:hover {
    background-color: #45a049;
}

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