Update sizing.md to clarify (0, 1] behavior.

Signed-off-by: Matthias <18034092+matthias-ccri@users.noreply.github.com>

Author: matthias-ccri

docs/data/system/sizing/sizing.md

@@ -19,9 +19,9 @@ Otherwise, it is directly set on the CSS property.
 
 ```jsx
 <Box sx={{ width: 1/4 }}> // Equivalent to width: '25%'
-<Box sx={{ width: 300 }}> // Numbers are converted to pixel values.
+<Box sx={{ width: 300 }}> // Numbers above 1 are treated as pixel values.
 <Box sx={{ width: '75%' }}> // String values are used as raw CSS.
-<Box sx={{ width: 1 }}> // 100%
+<Box sx={{ width: 1 }}> // 100% -- numbers in the range `(0, 1]` are treated as percentage values from 0 to 100%.
 ```
 
 ## Width