style.css

@import url('https://fonts.googleapis.com/css?family=Roboto');

*{
    margin: 0;
    padding: 0;
}

body {
    width: 100%;
    height: 100vh;
    background: #3498db;
    color: #ecf0f1;
    font-family: 'Roboto', sans-serif;
}

.container {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    width: 100%;
    height: 100vh;
}

h2 {
    font-size: 1.7em;
    color: #ecf0f1;
    font-weight: 900;
    margin-bottom: .1em;
}

span {
    color: #fff;
    font-size: 1em;
    font-weight: 500;
    margin: 0;
}

.form {
    margin: 2em 0;
    width: 25%;
    display: flex;
    flex-wrap: wrap;
}

input, button {
    width: 100%;
}

.cep {
    height: 32px;
    padding: .5em;
    font-size: 1.5em;
    text-align: center;
    border-radius: 3pxs;
    border: none;
    color: #000;
    background-color: #f2f2f2;
    outline: 0;
    box-shadow: 0 3px 6px rgba(0,0,0,0.16), 0 3px 6px rgba(0,0,0,0.23);
    transition: all .5s ease;
}

.cep:focus {
    box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);
    transition: all .5s ease;
}

.botao {
    margin-top: 1em;
    padding: .7em 2em;
    font-size: 1.3em;
    font-weight: 600;
    border: 2px solid #2ecc71;
    border-radius: 3px;
    cursor: pointer;
    outline: 0;
    background-color: #2ecc71;
    color: #ecf0f1;
    box-shadow: 0 3px 6px rgba(0,0,0,0.16), 0 3px 6px rgba(0,0,0,0.23);
}

.texto {
    margin: 1em 0;
    font-size: 1.5em;
    padding: .5em 0;
    transition: all  ease;
}
.esconde-campo {
    opacity: 0;
}
@media (max-width: 980px) {
    .form {
        width: 90%;
    }
    .texto {
        font-size: 1em;
        text-align: center;
        width: 90%;
    }
}