style.css

<style type="text/css">
table {
    border-spacing: 0;
    border-bottom: 2px solid black;
    border-top: 2px solid black;
}
table th {
    padding: 3px 10px;
    background-color: white;
    border-top: none;
    border-left: none;
    border-right: none;
    border-bottom: 1px solid black;
}
table td {
    padding: 3px 10px;
    border-top: none;
    border-left: none;
    border-bottom: none;
    border-right: none;
}
code {
    background-color: lightgrey;
}
</style>