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Rhythm is the repetition of elements in a regular pattern.

Gradation is a type of Rhythm were the elements stay in a regular pattern but can change color, size and value such as the case of the question which denotes a change in the workstationâ€(tm)s colors.

1009.11 Handrails .

Stairways shall have handrails on each side. Handrails shall be adequate in strength and attachment in accordance with Section 1607.7 . Handrails for ramps, where required by Section 1010.8 , shall comply with this section.
Exceptions:
1. Aisle stairs complying with Section 1024 provided with a center handrail need not have additional handrails .
2. Stairways within dwelling units, spiral stairways and aisle stairs serving seating only on one side are permitted to have a handrail on one side only.
3. Decks, patios and walkways that have a single change in elevation where the landing depth on each side of the change of elevation is greater than what is required for a landing do not require handrails .
4. In Group R-3 occupancies, a change in elevation consisting of a single riser at an entrance or egress door does not require handrails .
5. Changes in room elevations of only one riser within dwelling units and sleeping units in Group R-2 and R-3 occupancies do not require handrails .

1009.11.1 Height.
Handrail height, measured above stair tread nosings, or finish surface of ramp slope shall be uniform, not less than 34 inches (864 mm) and not more than 38 inches (965 mm).
Exceptions:
1. Handrails for stairs not required to be accessible that form part of a guardrail may be 42 inches (1067 mm) high.
2. In one- and two-family dwellings and within dwelling units in R2 occupancies, stairways having four or more risers above a floor or finished ground level shall be equipped with handrails located not less than 34 inches (864 mm) nor more than 38 inches (965 mm) above the leading edge of a tread.
handrails
1009.11.2 Intermediate handrails .
Handrails shall be provided within 30 inches (762 mm) of all portions of the stair width required for egress capacity in accordance with Table 1005.1 . The required egress width shall be along the natural path of travel.

1009.11.2.1
Where new intermediate handrails are provided in accordance with Section 1009.11.2 , the minimum clear width between handrails shall be 20 inches (510 mm).

1009.11.3 Handrail graspability.
Handrails with a circular cross section shall have an outside diameter of at least 1.25 inches (32 mm) and not greater than 2 inches (51 mm) or shall provide equivalent graspability. If the handrail is not circular, it shall have a perimeter dimension of at least 4 inches (102 mm) and not greater than 6.25 inches (160 mm) with a maximum cross-section dimension of 2.25 inches (57 mm). Edges shall have a minimum radius of 0.01 inch (0.25 mm).

1009.11.4 Continuity.
Handrail-gripping surfaces shall be continuous, without interruption by newel posts or other obstructions.
Exceptions:
1. Handrails within dwelling units are permitted to be interrupted by a newel post at a stair landing.
2. Within a dwelling unit, the use of a volute, turnout or starting easing is allowed on the lowest tread.
3. Handrail brackets or balusters attached to the bottom surface of the handrail shall not be considered to be obstructions to graspability, provided that the following conditions are met:
3.1. They do not project horizontally beyond the sides of the handrail within 1 1 / 2 inches (38 mm) of the bottom of the handrail and provided that, for eac h Â1/2 inch (12.7 mm) of additional handrail perimeter dimension above 4 inches (102 mm), the vertical clearance dimension of 1Â1/2 inches (38 mm) can be reduced by 1 / 8 inch (.3 mm).
3.2. They have edges with a radius of not less than .01 inch (.25 mm).
3.3. They obstruct not in excess of 20 percent of the handrail length.

1009.11.5 Handrail extensions.
Handrails shall return to a wall, guard or the walking surface or shall be continuous to the handrail of an adjacent stair flight. Where handrails are not continuous between flights, the handrails shall extend horizontally at least 12 inches (305 mm) beyond the top riser and continue to slope for the depth of one tread beyond the bottom riser.
Exceptions:
1. Handrails within a dwelling unit that is not required to be accessible need extend only from the top riser to the bottom riser.
2. Aisle handrails in Group A occupancies in accordance with Section 1024.13 .

1009.11.6 Clearance.
Clear space between a handrail and a wall or other surface shall be a minimum of 1.5 inches (38 mm). A handrail and a wall or other surface adjacent to the handrail shall be free of any sharp or abrasive elements.