Users hate coming across a PDF file while browsing

PDF is an undifferentiated blob of content

Oops, maybe if I let go of this apple, it will turn into a tomato and jump a mile into the sky.

they form their expectations for your site based on what's commonly done on most other sites

A wall of text is deadly

Intimidating. Boring. Painful to read.

Respect the user's preferences and let them resize text as needed. Also, specify font sizes in relative terms