Fireside embeds the Telerik wysiwyg (What You See Is What You Get) editor inside the product to generate HTML from a GUI (Graphical User Interface - basically buttons and menus instead of just text).
What this means is that when users change something in the menu, that has a corresponding effect on the HTML. The changes it makes are not always intuitive. A good rule of thumb is to work backward from the change you want to make in the HTML text, and seeing which changes in the editor will give you the desired effect.
When you copy and paste anything into the Telerik editor, it also copies and pastes any styling that the text has. As such, be sure to paste plain text into the editor, by hitting Ctrl + Shift + v, especially when pasting from Microsoft Word. There is also a Paste Plain Text button to the left of the undo button in the editor toolbar.
Fireside Web tools use the same Telerik editor as email newsletters. However, since webpages are rendered through the browser and not through an email client like Gmail, Outlook, or Apple Mail, the HTML is standards compliant and modern (unlike in email clients).
For webpages, nested tables don’t always make sense and can cause a lot of trouble, particularly if they have fixed widths. Instead, putting text inside of <p> tags, instead of a table, may work a lot better.