diff --git a/antora-playbook.yaml b/antora-playbook.yaml
index cb73957..21775ef 100644
--- a/antora-playbook.yaml
+++ b/antora-playbook.yaml
@@ -67,11 +67,23 @@ ui:
         <!-- `@asciidoctor/tabs` extension styles -->
         <link rel="stylesheet" href="{{{uiRootPath}}}/css/vendor/tabs.css">
         <style>
+          /* Default `h4` and `h5` are smaller than the normal text, fix header font sizing: */
+          .doc h1 { font-size: 1.9rem; }
+          .doc h2 { font-size: 1.7rem; }
+          .doc h3 { font-size: 1.5rem; font-weight: 400; }
+          .doc h4 { font-size: 1.3rem; font-weight: 500; }
+          .doc h5 { font-size: 1.1rem; font-weight: 500; text-decoration: underline; }
+          /* Default `code`, `pre`, and `.colist` (source code annotations) fonts are too big, adjust them: */
+          .doc .colist>table code, .doc p code, .doc thead code { font-size: 0.8em; }
+          .doc pre { font-size: 0.7rem; }
+          .doc .colist { font-size: 0.75rem; }
+          /* Tab header fonts aren't rendered good, adjusting the font weight: */
+          .tablist > ul li { font-weight: 500; }
           /* `page-toclevels` greater than 4 are not supported by Antora UI, patching it: */
           .toc .toc-menu li[data-level="4"] a {
-            padding-left: 2.75rem
+            padding-left: 2.75rem;
           }
-          /* Replace the default highlight.js color for strings from red to green: */
+          /* Replace the default highlight.js color for strings from red (unnecessarily signaling something negative) to green: */
           .hljs-string {
             color: #0f8532;
           }