mdBook/src/theme/css/print.css

@media only print {

    #sidebar,
    #menu-bar,
    .nav-chapters,
    .mobile-nav-chapters {
        display: none;
    }

    #page-wrapper.page-wrapper {
        transform: none;
        margin-left: 0px;
        overflow-y: initial;
    }

    #content {
        max-width: none;
        margin: 0;
        padding: 0;
    }

    .page {
        overflow-y: initial;
    }

    code {
        background-color: #666666;
        border-radius: 5px;

        /* Force background to be printed in Chrome */
        -webkit-print-color-adjust: exact;
    }

    pre > .buttons {
        z-index: 2;
    }

    a, a:visited, a:active, a:hover {
        color: #4183c4;
        text-decoration: none;
    }

    h1, h2, h3, h4, h5, h6 {
        page-break-inside: avoid;
        page-break-after: avoid;
    }

    pre, code {
        page-break-inside: avoid;
        white-space: pre-wrap;
    }

    .fa {
        display: none !important;
    }
}