is this the answer?
first goog hit
stairs
Exterior landings shall be permitted to have a slope not to exceed 1/4 unit vertical in 12 ... Stair treads and risers shall meet the requirements of this section. For the purposes of ... For interior stairs the artificial light sources shall be capable of.
Stair angles depennd on the space available
A good ratio is 2/1
A 6.5” riser and a 13” tread at an incline of about 32 degrees.