Please post a link to your pages online somewhere so that we can see what you see - make your HTML code > More Readable in File>Document Setup>Output (2nd dropdown selector) and we can read your code as well.
We will try and anticipate your problem whenever we can but seeing it makes it so much easier for us to give a properly considered answer.
not sure if this helps but I’ve found you sometimes need to quit Safari and relaunch after you make alterations - I’ve had odd previews when I’ve made changes but they show OK when you quit/relaunch