It is important to note for this to work you need a font with all the appropriate weights. I don’t have one but The guardian sans has 9 weights but for some reason only 7 are being used, Futura BT has 5, Myriad pro has 5, Helvetica neue has 4, Gill sans has 3,

You are unlikely to have gardian sans or a futura with 5 weights, I’m not sure how to make a better test case.

1. This is normal lighter
2. This is normal (same as 400)
3. This is normal bolder
4. This is bold
5. This is bold lighter (same as normal)

1. This is 100
2. This is 200
3. This is 300
4. This is 400 (same as normal)
5. This is 500
6. This is 600
7. This is 700
8. This is 800
9. This is 900

1. This is 100 bolder
2. This is 200 bolder
3. This is 300 bolder (same as normal)
4. This is 400 bolder
5. This is 500 bolder
6. This is 600 bolder
7. This is 700 bolder
8. This is 800 bolder
9. This is 900 bolder

1. This is 100 lighter
2. This is 200 lighter
3. This is 300 lighter
4. This is 400 lighter
5. This is 500 lighter (same as normal)
6. This is 600 lighter
7. This is 700 lighter
8. This is 800 lighter
9. This is 900 lighter