Sizes stay at 16px. This dials on-screen stroke width. The master slider sets one uniform stroke for the whole toolbar (lucide's default at 16px is 1.33px). The per-icon sliders let you thin a heavy glyph (e.g. Sticky note / Save) below the others. Row 1 = today (1.33px uniform). Tune row 2, then Copy the readout back into the chat.
strokeWidth × size / 24. At size 16 the strokeWidth attribute passed to
the icon = screenPx × 1.5. The plan turns the chosen values into either one toolbar stroke token or a
per-glyph stroke map.