body{
    background-color: black;
    text-align: center;
}
div{
    background-color: lightgreen;
}
.header{
    position: relative;
}
h1{
    color: darkgreen;
}
.buttons{
    position: absolute;
    right: 20px;
    top: 10px;
}
p{
    font-size: 1.2em;
    font-family: Arial, Helvetica, sans-serif;
    color: rgb(5, 0, 139);
}
span{
    font-weight: bold;
    color: darkred;
    background-color: lightslategray;
}
.tables{
    display: inline-block;
    margin-top: 10px;
    background-color: lightpink;
}
table, th, td {
    border: 1px solid;
    text-align: start;
    border-radius: 5px;
    margin: 2em;
    padding: 5px;
}
.table--commands{
    background-color: lightyellow;
}
.table--abbreviations{
    background-color: lightcyan;
}