body {
    font-family: 'Inter', Arial, sans-serif;
    background: #F9FAFB;
    margin: 0;
    padding: 0;
}

.container {
    max-width: 480px;
    margin: 40px auto;
    background: rgba(255, 255, 255, 0.85);
    padding: 30px;
    border-radius: 14px;
    box-shadow: 0 4px 18px rgba(0,0,0,0.08);

    /* 🔥 Fondo tropical detrás del recuadro */
    background-image: url('background.png');
    background-size: cover;
    background-position: center;
}

h1 {
    text-align: center;
    color: #0F172A;
}

h3 {
    margin-top: 25px;
    color: #334155;
}

.input-group {
    margin-bottom: 15px;
}

label {
    font-weight: 600;
    display: block;
    margin-bottom: 5px;
    color: #475569;
}

input {
    width: 100%;
    padding: 12px;
    border-radius: 8px;
    border: 1px solid #CBD5E1;
    font-size: 15px;
}

button {
    width: 100%;
    padding: 14px;
    background: #00BFA6;
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 17px;
    cursor: pointer;
    margin-top: 10px;
    transition: 0.3s;
}

button:hover {
    background: #009E8A;
}

.resultado {
    margin-top: 20px;
    padding: 18px;
    border-radius: 10px;
    font-size: 18px;
    text-align: center;
    font-weight: bold;
}

footer {
    text-align: center;
    margin-top: 30px;
    padding: 20px;
    font-size: 14px;
    color: #475569;
    background: linear-gradient(to right, #00BFA6, #FCD34D);
    border-radius: 0 0 12px 12px;
}

footer a {
    color: #0F172A;
    text-decoration: none;
    font-weight: 600;
}

footer a:hover {
    color: #2563EB;
}