NOT to be confused with Custom Embed Code. 

There are numerous instances where it makes more sense to write properties directly into HTML instead of a css/class. 

For example, I don't want to make a NEW CSS class name for

'<'p'>'<'font size="20px"'>'This is some text!'<'/font'>'<'/p'>' 

This is some text!

I simply want that particular paragraph element to be 20px in HTML without making new class-name.

Basically, a good way to incorporate this is using the existing Style Panel with a 'Bypass CSS' pill toggle, which Style panel writes directly into HTML without css.

NOT to be confused with Custom Embed Code.

When using DIV Attributes, it doesn't work in Designer.