Graham
toshudhiman Oh your on about the building tool css editor "custom css" is used to define any css property not covered by the other options the property name goes in the first input and the value goes in the second
but you still need to know which css property you wish to define and what value you want to give it
The building tool css editor is for css that is exclusive to that page
It creates <style>...</style> tags and css data in the pages <head> area
You define classes which you select for an item in the main building tool you cannot define global classes for html tags with it
to define a class give it a name (ignore pseudo class for now that is for advanced use and the various states of a link)
then add values to any of the preset properties or define a property / value pair in the custom css
