updating stylesheet to make printing cleaner from HTML

Tima had feedback that saving the HMTL to a PDF wasn't ideal for printing, as the marking ad
took up 1/3 of the page. We've cleaned up the ad as well as streamlined printing a bit (removing
color backgrounds from admonitions and adding black text, exposing links, etc.)

docsite/_themes/srtd/static/css/theme.css

@@ -4736,3 +4736,23 @@ span[id*='MathJax-Span'] {
 .DocSiteBanner-imgWrapper {
     max-width: 100%;
 }
+
+@media print {
+    * { background: transparent !important; color: black !important; text-shadow: none !important; filter:none !important; -ms-filter: none !important; }
+    #nav,
+    a, a:visited { text-decoration: underline; }
+    a[href]:after { content: " (" attr(href) ")"; }
+    abbr[title]:after { content: " (" attr(title) ")"; }
+    .ir a:after, a[href^="javascript:"]:after, a[href^="#"]:after { content: ""; }  /* Don't show links for images, or javascript/internal links */
+    pre, blockquote { border: 0px solid #999; page-break-inside: avoid; }
+    thead { display: table-header-group; } /* h5bp.com/t */
+    tr, img { page-break-inside: avoid; }
+    img { max-width: 100% !important; }
+    @page { margin: 0.5cm; }
+    p, h2, h3 { orphans: 3; widows: 3; }
+    h2, h3 { page-break-after: avoid; }
+    .DocSiteBanner,
+    #google_image_div {
+        display: none !important;
+    }
+