Custom CSS on page

The CSS code added below will only be applied to the currently previewed page, not site wide.

Hi guys please help me here, if im not mistaken if i save the css code it should work on the selected page only , but when i save and close the editor it does not show at all on the page ?

it works fine again when i open the editor

the page
https://choiceofficefurniture.co.za/desks/
the code

.prod-cat-inner {
	width: 107%;
}