Physical Shape Cookbook

Guidance for drawing physical objects (vehicles, buildings, hardware, mechanical systems, anatomy) — when rectangles aren't enough.

Shape selection

Physical form	SVG element	Example use
Curved bodies	`<path>` with Q/C curves	Fuselage, tanks, pipes
Tapered/angular shapes	`<polygon>`	Wings, fins, wedges
Cylindrical/round	`<ellipse>`, `<circle>`	Engines, wheels, buttons
Linear structures	`<line>`	Struts, beams, connections
Internal sections	`<rect>` inside parent	Compartments, rooms
Dashed boundaries	`stroke-dasharray`	Hidden parts, fuel tanks

Layering approach

Draw outer structure first (fuselage, frame, hull)
Add internal sections on top (cabins, compartments)
Add detail elements (engines, wheels, controls)
Add leader lines with labels

Semantic CSS classes (instead of c-* ramps)

For physical diagrams, define component-specific classes directly rather than applying c-* color classes. This makes each part self-documenting and lets you keep a restrained palette:

css

.fuselage { fill: #F1EFE8; stroke: #5F5E5A; stroke-width: 1; }
.wing     { fill: #E6F1FB; stroke: #185FA5; stroke-width: 1; }
.engine   { fill: #FAECE7; stroke: #993C1D; stroke-width: 1; }

Add these to a local <style> inside the SVG (or extend the host page's <style> block). The light-mode/dark-mode pattern still works — use the CSS variables from the template (var(--bg-secondary), var(--border), var(--text-primary)) if you want dark-mode awareness.

Reference examples

Look at these example files for working physical-diagram patterns:

examples/commercial-aircraft-structure.md — fuselage curves + tapered wings + ellipse engines
examples/wind-turbine-structure.md — underground foundation, tubular tower, nacelle cutaway
examples/smartphone-layer-anatomy.md — exploded-view stack with alternating labels
examples/apartment-floor-plan-conversion.md — walls, doors, windows, proposed changes