From 5dd2f37ed5916cf9f8298171179e17cf7ab8a2a0 Mon Sep 17 00:00:00 2001
From: cyphercodes <cyphercodes@users.noreply.github.com>
Date: Mon, 1 Jun 2026 06:19:35 +0300
Subject: [PATCH] Fix luminance with non-integer color channels

---
 scss/_functions.scss                      |  2 +-
 scss/tests/functions/_luminance.test.scss | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 scss/tests/functions/_luminance.test.scss

diff --git a/scss/_functions.scss b/scss/_functions.scss
index 59d431a15b93..50122076eb18 100644
--- a/scss/_functions.scss
+++ b/scss/_functions.scss
@@ -188,7 +188,7 @@ $_luminance-list: .0008 .001 .0011 .0013 .0015 .0017 .002 .0022 .0025 .0027 .003
   );
 
   @each $name, $value in $rgb {
-    $value: if(divide($value, 255) < .04045, divide(divide($value, 255), 12.92), nth($_luminance-list, $value + 1));
+    $value: if(divide($value, 255) < .04045, divide(divide($value, 255), 12.92), nth($_luminance-list, min(255, max(0, round($value))) + 1));
     $rgb: map-merge($rgb, ($name: $value));
   }
 
diff --git a/scss/tests/functions/_luminance.test.scss b/scss/tests/functions/_luminance.test.scss
new file mode 100644
index 000000000000..55b4575ff864
--- /dev/null
+++ b/scss/tests/functions/_luminance.test.scss
@@ -0,0 +1,22 @@
+@import "../../functions";
+
+// Simulate Sass color channel functions returning non-integer channel values.
+@function red($color) {
+  @return 241.5;
+}
+
+@function green($color) {
+  @return 135.5;
+}
+
+@function blue($color) {
+  @return 8.5;
+}
+
+@include describe("luminance function") {
+  @include it("should round non-integer channel values before reading the luminance table") {
+    $result: luminance(#f7941c);
+
+    @include assert-true($result > 0 and $result < 1, "Non-integer color channels should not crash luminance()");
+  }
+}