.box {
    max-width: 1000px;
    margin: 50px auto;
    display: grid;
    grid-gap: 10px;
    grid-template-columns: 200px minmax(0,1fr);

}

header { border: blue 2px solid;
    background-color: blue;
}
header {
    font-family: Helvetica, sans-serif;
    color:rgb(255, 255, 255);
    text-align: center;
    grid-row: 1 / 2;
    grid-column: 1 / 3;
}

nav, main { border: blue 2px solid;
}

nav {
    font-family: Helvetica, sans-serif;
    color:blue;
    text-indent: 10px; /* O 5%,*/;
    grid-row: 2 / 4;
    grid-column: 1 / 2;
    height: max-content;
}

main {
    font-family: Helvetica, sans-serif;
    color:blue;
    padding-left: 10px;
    padding-right: 10px;
    padding-bottom: 10px;
    grid-row: 2 / 4;
    grid-column: 2 / 3;
    height: max-content;
}


imgfooter, footer { border: transparent;
}

imgfooter {
    text-align: center;
    grid-row: 4 / 5;
    grid-column: 1 / 3;
}

footer {
    font-family: Helvetica, sans-serif;
    color:blue;
    text-align: center;
    grid-row: 5 / 6;
    grid-column: 1 / 3;
}