Fix typo in CSS substitution example.
@@ -415,7 +415,7 @@ Original entity: `<div style="color: {$x}">`
Value | Substitution
---------------------------------------- | ----------------------------
`({ "x": "red" })` | `<div style="color: red">`
-`({ "x": "#f00" })` | `<div style="color: #foo">`
+`({ "x": "#f00" })` | `<div style="color: #f00">`
`({ "x": "expression('alert(1337)')" })` | `<div style="color: zSoyz">`
##### Property Names
