style: align code style with guides-source

Author: IgnaceMaes

app/styles/app.css

@@ -0,0 +1,26 @@
+/* Make code blocks denser */
+
+.chapter pre, .chapter pre[class*=language-],
+.chapter code, .chapter code[class*=language-] {
+  line-height: 1.6;
+}
+.chapter .filename, .chapter pre, .chapter pre[class*=language-], .filename::after {
+  font-size: 85%;
+}
+
+.filename::after {
+  margin-top: 0;
+  margin-bottom: 0;
+}
+
+.chapter .filename {
+  padding-top: var(--spacing-1);
+  padding-bottom: var(--spacing-1);
+}
+.chapter .filename + pre code {
+  padding: var(--spacing-1) 0;
+}
+
+.shiki code {
+  font-size: 1em !important;
+}