Charles Nicholson contributed to the ghostty-org/ghostty repository by addressing a UI rendering bug that affected grid layout consistency across devices. He focused on refining the cell width calculation, shifting from a ceiling to a rounding approach to better align with CoreText glyph advances. This adjustment improved horizontal spacing, particularly on non-Retina displays, while maintaining the existing ceiling method for vertical space to preserve cell height behavior. Working primarily in Zig, Charles applied his skills in algorithm optimization and font rendering to reduce layout jitter and enhance readability in dense data views, resulting in fewer user-reported UI issues on affected screens.