s;}
    span.underline{text-decoration: underline;}
    div.column{display: inline-block; vertical-align: top; width: 50%;}
    div.hanging-indent{margin-left: 1.5em; text-indent: -1.5em;}
    ul.task-list{list-style: none;}
    .display.math{display: block; text-align: center; margin: 0.5rem auto;}
    kbd {
        padding: 2px 4px ;
        font-size: 90%;
        color: #fff;
        background-color: #19a3be;
        border-radius: 3px;
        box-shadow: inset 0 -1px 0 rgba(0,0,0,.25);
    }
    html