Read the README.md file within this skill, and explore the other available files. If creating visual artifacts (slides, mocks, throwaway prototypes, etc), copy assets out and create static HTML files for the user to view. If working on production code, you can copy assets and read the rules here to become an expert in designing with this brand. If the user invokes this skill without any other guidance, ask them what they want to build or design, ask some questions, and act as an expert designer who outputs HTML artifacts or production code, depending on the need.

Quick orientation:

styles.css is the single CSS entry point — link it and use the CSS custom properties (never hard-code hex). Dark is the default; add data-theme="light" on a wrapper for the light palette.
Type: Geist (UI) + Geist Mono (numbers/technical). Base 13px.
One brand hue: emerald --accent. Ration it. Timeline lanes add amber/orange/red semantic accents.
Components live in components/ (forms, display, editor); full-screen recreations in ui_kits/editor/. Icons are Lucide.
No emoji, no gradients-as-decoration, no photographic backgrounds. Dense pro-tool density, glassy floating panels, hairline borders.
Editor controls (full rules: "EDITOR CONTROLS" in readme.md): a fixed choice is a one-click ChoiceRow, not a select; named levels instead of meaningless numbers; settings are free rows under sentence-case section labels, never cards; no hint text, and an option that does nothing is hidden, not disabled.
Timeline is "candy": the clip is the brand green, zooms blue, every lane solid with dark ink #0b1220; playhead violet; no seek bar.

openscreen-design