main {
    align-content: center;
    margin: auto;
    width:90%;
}


.subtitle {
    text-transform: uppercase;
    text-align: center;
}

.boxes {
    content: "";
    display: table;
    clear: both;
    margin:auto;
}

.boxes > div {
    float: left;
    height: 3rem;
    width: 4rem;
    padding: 2rem 2rem 0rem;
    margin: .5rem;
    font-size: 1.75rem;
    border: solid black 1px;
    text-align: center;
    font-weight: 600;    
}

.numbers > div {
    background-color: aqua;
    font-weight: 700;  
}

.binary >div {
    background-color:floralwhite;
}

.boxlarge {
    /*content: "";*/
    display: table;
    clear: both;
    /*align-items: center;*/
    margin:auto;
}

.boxlarge > div {
    float: inherit;
    height: 3rem;
    width: 4rem;
    padding: 2rem 2rem 0rem;
    margin: .5rem;
    font-size: 1.75rem;
    border: solid black 1px;
    text-align: center;
}

#decimal {
    background-color: green;
    color: white;
    font-weight: 700;
}

.intro {
    padding-left: 10rem;
}

.sub-heading {
    text-align: center;
    text-transform: capitalize;
}