The fixed 3-column grid overflows below ~768px because nothing
adapts the layout for small screens.

Assisted-by: Claude Opus 4.6 via Claude Code

diff --git a/public/css/app.css b/public/css/app.css
index 854f697..a26365b 100644
--- a/public/css/app.css
+++ b/public/css/app.css
@@ -92,6 +92,17 @@ h2 { font-size: var(--step-0); font-weight: 600; }
   margin-inline: auto;
 }
 
+@media (max-width: 48rem) {
+  .home {
+    grid-template-columns: 1fr;
+    gap: var(--space-l);
+  }
+
+  .column-aside {
+    width: auto;
+  }
+}
+
 .column {
   min-width: 0;
 }