refactor: simplify the quartoorg site code (#2298)

* refactor: simplify the quartoorg site code

The light and dark themes now share one announcement banner rule, and the
prerelease banner only overrides its colour. The navbar drops a selector
for an icon the site no longer uses. The page tweaks script detects macOS
from the user agent instead of the deprecated navigator.platform, and
marks pymd comments with a class instead of setting the font weight
inline.

* chore: remove unused images

Two are backups of older renders that nothing ever referenced, and two
are home page drafts from March 2023 that newer images replaced.

* refactor: drop the scope on the pymd comment rule

Author: mcanouil

_extensions/quartoorg/assets/scripts/page-tweaks.html

@@ -1,7 +1,7 @@
 <script type="text/javascript">
 
 // replace cmd keyboard shortcut w/ control on non-Mac platforms
-const kPlatformMac = typeof navigator !== 'undefined' ? /Mac/.test(navigator.platform) : false;
+const kPlatformMac = /Macintosh/.test(navigator.userAgent);
 if (!kPlatformMac) {
    var kbds = document.querySelectorAll("kbd")
    kbds.forEach(function(kbd) {
@@ -12,7 +12,7 @@
 // tweak headings in pymd
 document.querySelectorAll(".pymd span.co").forEach(el => {
    if (!el.innerText.startsWith("#|")) {
-      el.style.fontWeight = 1000;
+      el.classList.add("pymd-comment");
    }
 });
 

_extensions/quartoorg/scss/partials/_announcement.scss

@@ -0,0 +1,11 @@
+#quarto-announcement {
+  padding: 1em;
+  font-size: 1em;
+  font-weight: bold;
+  color: $white;
+  background-color: #447099;
+}
+
+#quarto-announcement a {
+  color: $white;
+}

_extensions/quartoorg/scss/partials/_content.scss

@@ -70,3 +70,9 @@ table.quarto-listing-table .listing-description a {
 pre.sourceCode.visually-hidden {
   overflow: hidden !important;
 }
+
+/* page-tweaks.html marks the comments in .pymd blocks that are not
+   `#|` cell options. */
+.pymd-comment {
+  font-weight: 1000;
+}

_extensions/quartoorg/scss/partials/_dark-rules.scss

@@ -90,18 +90,6 @@ details > summary {
   color: $text-muted;
 }
 
-#quarto-announcement {
-  padding: 1em;
-  font-size: 1em;
-  font-weight: bold;
-  color: $white;
-  background-color: #447099; 
-}
-
-#quarto-announcement a {
-  color: $white;
-}
-
 /*Footer Posit logo color for dark mode*/
 
 img.footer-logo {

_extensions/quartoorg/scss/partials/_light-rules.scss

@@ -34,15 +34,3 @@
   text-align: right;
   padding-right: 1em;
 }
-
-#quarto-announcement {
-  padding: 1em;
-  font-size: 1em;
-  font-weight: bold;
-  color: $white;
-  background-color: #447099; 
-}
-
-#quarto-announcement a {
-  color: $white;
-}

_extensions/quartoorg/scss/partials/_navbar.scss

@@ -18,7 +18,6 @@
   margin-left: .1em;
 }
 
-.navbar .bi-twitter,
 .navbar .bi-github,
 .navbar .bi-rss
  {

_extensions/quartoorg/scss/partials/_site.scss

@@ -12,3 +12,4 @@
 @import "figures";
 @import "color-box";
 @import "home";
+@import "announcement";

_extensions/quartoorg/scss/prerelease-banner.scss

@@ -4,8 +4,5 @@
 // #e60033 gives white text 4.76:1 (WCAG 1.4.3 needs 4.5:1).
 // Cosmo's $danger (#ff0039) gives only 3.95:1.
 #quarto-announcement {
-  font-size: 1em;
-  font-weight: bold;
-  color: $white;
   background-color: #e60033;
 }