@media(max-width: 750px){ /*se a tela for menor que 750px aplicar o codigo abaixo*/
    section{
        flex-direction: column;
        padding: 15px 0px;
        align-items: center;
    }

    .cartao{
        max-width: 340px;
    }

    h3{
        font-size: 16px;
    }

    nav{
        max-width: 340px;
    }

    nav ul{
        display: flex;
        justify-content: center;
        align-items: center;
        flex-wrap: wrap;
        gap: 8px;
    }

    li{
        border-radius: 50px;
        width: 40%;
        margin: 0px;
    }
}