Turning off the style sheets and images (with the alt text showing) is a good way to find out if your static content stands on its own or not. When the content is stripped bare like this, it is sort of how a screen reader "sees" it.
Avoid Referencing Color, Size, Location, Position, or Sound in Instructions or Help Information:
Any time we reference size, location, position, or sound in information, we're relying on the presence of a specific sense (or senses) on the part of our user, which he or she may not have.
Bad Example
... the larger area represents ...
Good Example
... the alert will display when ...