diff --git a/flex/07-flex-layout-2/solution/solution.css b/flex/07-flex-layout-2/solution/solution.css
index 3ca1867..eb082a3 100644
--- a/flex/07-flex-layout-2/solution/solution.css
+++ b/flex/07-flex-layout-2/solution/solution.css
@@ -50,6 +50,7 @@ body {
 .sidebar {
   flex-shrink: 0;
   padding: 16px;
+  box-sizing: border-box;
 }
 
 ul {