Ask for width in a loop that repeats if input isn't 1 - 400
Ask for length in a loop that repeats if input isn't 1 - 400

area = ((width * length) / 2) / 10000
ratio = width / length
mass = area * 135
force = (mass / 1000) * 9.8

print width, length, and ratio labeled with units
if ratio >= 1 print warn the user that the kite could be unstable
print area, mass, and gravity labeled with units