Why is it important to avoid these features?

• Text in all uppercase is significantly more difficult to read than lower and mixed case text. It’s best to write online in sentence case or mixed case, with proper nouns capitalized as well as the first letter of the first word. That is how people are used to reading printed material.
• Avoid text with shadows. It changes the shape of the letters the reader has come to know. Shadowed text also limits the contrast between the letters and the background.
• Print types such as italics and excessibve underline make it more difficult to differentiate among letters.

Better choices are: Underscoring, “enclosing in quotation marks,” or bolding.