Grid Calibration

I crossed the threshold onto the second-floor landing. A yellow rectangular warning label had detached from the fire door and rested askew over the concrete floor groove. I halted three centimeters before the seam. Bending my knee joints with steady calibration, I pressed two rigid fingertips against the stiff edge of the plastic card. I shifted it forty-five degrees until its long boundary ran perfectly parallel to the dark expansion gap. The yellow surface caught a sharp reflection from the overhead stair lamp. Orientation secured.