/* Reset básico */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

/* Body */
body {
    background: #f2f2f2;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    min-height: 100vh;
    padding: 50px 20px;
}

/* Título principal */
h2 {
    color: #333;
    margin-bottom: 30px;
    font-size: 2em;
    text-align: center;
}

/* Formulario */
form {
    display: flex;
    flex-direction: column;
    gap: 15px;
    background: #fff;
    padding: 30px 40px;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 400px;
}

/* Input de número */
input[type="number"] {
    padding: 10px 15px;
    font-size: 1em;
    border: 1px solid #ccc;
    border-radius: 5px;
    outline: none;
    transition: 0.3s;
}

input[type="number"]:focus {
    border-color: #007bff;
    box-shadow: 0 0 5px rgba(0, 123, 255, 0.3);
}

/* Botón enviar */
input[type="submit"] {
    padding: 12px;
    font-size: 1em;
    border: none;
    border-radius: 5px;
    background: #007bff;
    color: white;
    cursor: pointer;
    transition: 0.3s;
}

input[type="submit"]:hover {
    background: #0056b3;
}

/* Resultado */
h3 {
    margin-top: 30px;
    background: #fff;
    padding: 20px 30px;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    color: #007bff;
    font-size: 1.5em;
    text-align: center;
}