Apple iMac (Early 2008) - Manual (Page 61)

Chapter 5 Last, but Not Least 61
You may have to raise your chair so that your forearms and hands are at the proper
angle to the keyboard. If this makes it impossible to rest your feet flat on the floor,
you can use a footrest with adjustable height and tilt to make up for any gap between
the floor and your feet. Or you may lower the desktop to eliminate the need for a
footrest. Another option is to use a desk with a keyboard tray that’s lower than the
regular work surface.
Display
Arrange the display so that the top of the screen is slightly below eye level when you’re
sitting at the keyboard. The best distance from your eyes to the screen is up to you,
although most people tend to prefer 18 to 28 inches (45 to 70 cm). Position the display
to minimize glare and reflections on the screen from overhead lights and windows.
Thighs tilted
slightly
Shoulders
relaxed
Screen positioned to
avoid reflected glare
Forearms and
hands in a
straight line
Forearms level
or tilted slightly
Lower back
supported
Feet flat on the floor
or on a footrest
Top of the screen at or
slightly below eye level
Clearance under
work surface
45–70 cm (18–28 in.)