diff --git a/core/src/components/thumbnail/readme.md b/core/src/components/thumbnail/readme.md
index 355f7347e9..c170499bbe 100644
--- a/core/src/components/thumbnail/readme.md
+++ b/core/src/components/thumbnail/readme.md
@@ -8,6 +8,13 @@ Thumbnails can be used by themselves or inside of any element. If placed inside
+## CSS Custom Properties
+
+| Name | Description |
+| ----------------- | ------------------------------ |
+| `--border-radius` | Border radius of the thumbnail |
+| `--size` | Size of the thumbnail |
+
----------------------------------------------
diff --git a/core/src/components/thumbnail/test/standalone/index.html b/core/src/components/thumbnail/test/standalone/index.html
index 1700e29a39..028d3a35f1 100644
--- a/core/src/components/thumbnail/test/standalone/index.html
+++ b/core/src/components/thumbnail/test/standalone/index.html
@@ -13,5 +13,16 @@
+
+
+
+
+
+