Make markdown synchronous and add ability to toggle TOC

web-app/template-styles/blog-styles.css

@@ -30,3 +30,7 @@ footer {
   flex-direction: column;
   gap: var(--space-xs);
 }
+
+.table-of-contents {
+  margin-block-end: var(--space-s);
+}

web-app/template-styles/common-styles.css

@@ -210,3 +210,12 @@ td {
   padding-block: var(--space-3xs);
   border: var(--border-primary);
 }
+
+summary {
+  cursor: pointer;
+}
+
+:is(a, summary):focus {
+  outline: 0.125rem solid var(--color-accent);
+  outline-offset: 0.25rem;
+}