diff --git a/readme.md b/readme.md
index e69de29..5865806 100644
--- a/readme.md
+++ b/readme.md
@@ -0,0 +1,7 @@
+<!-- @format -->
+
+Git is case-sensitive → it sees readme.md and README.md as different files.
+
+Windows/macOS are case-insensitive → they treat both names as the same file.
+
+So when you rename only the case, the OS says "nothing changed," and Git doesn’t record it.