div.formulario {
    max-width: 700px;
    margin: 0px auto;
    padding: 20px;
    border: 1px solid lightgrey;
    border-radius: 5px;
    background-color: lightgrey ;
    border: 1px solid black;
    margin-top: 120px;
}

div.nombre,div.correo,div.mensaje {
    margin-bottom:30px;
}

label {
    display: block;
    font-weight: bold;
}

input[type="text"],
input[type="email"],
textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid black;
    border-radius: 5px;
    box-sizing: border-box; 
}

div.boton input[type="submit"] {
    background-color: black;
    color: white;
    border: none;
    padding: 10px 20px;
    font-size: 16px;
    border-radius: 5px;
    cursor: pointer;
}

div.boton input[type="submit"]:hover {
    background-color: green;
}

div.conocenos fieldset label{
    margin: 10px;

}