diff --git a/.changeset/happy-ways-suffer.md b/.changeset/happy-ways-suffer.md
new file mode 100644
index 00000000..0886b72d
--- /dev/null
+++ b/.changeset/happy-ways-suffer.md
@@ -0,0 +1,5 @@
+---
+'@primer/css': patch
+---
+
+Prevents main content to blowout and cause an horizontal scroll
diff --git a/src/layout/layout.scss b/src/layout/layout.scss
index 477a9a85..20b4b586 100644
--- a/src/layout/layout.scss
+++ b/src/layout/layout.scss
@@ -152,6 +152,7 @@
 }
 
 .Layout-main {
+  min-width: 0;
 
   // Centered main column
   // FIXME: right-aligned sidebar