body {
    background-image: url(Fons_arqtecnic2012.gif);
    background-size: auto;
    background-attachment: fixed;
    margin: 0;
    font-family: sans-serif;
}
form {
    width: 450px;
    margin: auto;
    background: rgba(0,0,0,0.4);
    padding: 10px 20px;
    box-sizing: border-box;
    margin-top: 20px;
    border-radius: 7px;
}

h2 {
   color: dimgrey;
    text-align: center;
    margin: 0;
    font-size: 40px;
    margin-bottom: 20px;
}

h3 {
   color: black;
    text-align: right;
    margin: 100px;
    font-size: 30px;
    margin-top: 0px;
    margin-bottom: 5px;
}

input, textarea {
    width: 100%;
    margin-bottom: 20px;
    padding: 7px;
    box-sizing: border-box;
    font-size: 17px;
    border: none;
}

textarea {
    min-height: 100px;
    max-height: 200px;
    max-width: 100%;
}

#boto {
    background: #31384A;
    color: white;
    padding: 20px;
}

#boto:hover {
    cursor: pointer;
}

@media (max-width:480px) {
    form {
        width: 100%;
    }
}
h1 {
    text-align: center;
    color: white;
    font-size: 50px;
    background: rgba(1,1,1,0.3);
    margin-top: 20px;
    margin-bottom: 20px;
}
body {
    
}