body {
 width: 95%;
 max-width: 800px;
 margin: auto;
 background: url(back.jpg) center;
line-height: 1.5;
color: black;
}

.logo { 
    display: flex;
    justify-content: center;
    align-items: center;

}

main {
    background: rgb(172 211 234 / 71%);
    padding: 5px 40px;
    margin-top: 20px;
    border-radius: 20px;
} 

#mensagem {
    width: 400px;
    height: 200px;
}



#logo {
    text-align: center;
}

.welcome, .root, .insira, .chave, .result, .button {
    margin: 0;
    text-align: center;
}