{"slug":"icons","title":"icons","summary":"Designing SVG geometry for Cerb's icon set -- the four pattern families, the fixed outer template, and the mask-image constraints that make ordinary SVG instincts wrong. Load it before drawing or editing any icon.","platform":"Claude","tags":[],"authorName":"LLM Mart","authorSlug":"llm-mart","score":0,"source":"github","price":null,"verified":false,"createdAt":"2026-10-16T16:27:57.296316Z","repo":{"url":"https://github.com/jstanden/cerb","stars":84,"forks":38,"license":null,"updatedAt":"2026-10-16T15:09:59Z"},"bodyHtml":"
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name: icons\ndescription: Designing SVG geometry for Cerb's icon set -- the four pattern families, the fixed outer template, and the mask-image constraints that make ordinary SVG instincts wrong. Load it before drawing or editing any icon.

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Cerb SVG icons

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Cerb icons live in an SCSS Sass map and render via CSS mask-image. The icon's geometry determines opacity; the button's CSS text color provides the actual visible color. Fill and stroke are both just \"opaque\" — there is no color contrast available. Every visual distinction must come from geometry: opaque shape vs transparent gap.

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Output format

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Each icon is a single line in a Sass map:

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  name:           \"<inner-svg-geometry>\",\n
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The geometry is strictly inner geometry. Never include the <svg> tag (start or end), </svg> closing tags, <g> groups, or xmlns attributes. Just the shapes and paths. Use single quotes on SVG attributes so the whole thing fits in the double-quoted Sass string.

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Outer template (applied automatically at render time)

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  <svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'\n     fill='none' stroke='black' stroke-width='2'\n     stroke-linecap='round' stroke-linejoin='round'>\n  ...your inner geometry here...\n  <!-- The closing </svg> is added automatically -->\n</svg>\n
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Your geometry inherits:

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The four pattern families

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Pick a family up front and design within its constraints. Combining families in one icon usually fails because of the mask-image color limitation.

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1. Line icon (Lucide style, default). <path>, <rect>, <circle>, <line>, <polyline>, <polygon> with no extra attributes — they inherit fill='none', stroke='black' stroke-width='2'. Covers the vast majority of icons.

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  mail:           \"<rect x='2' y='4' width='20' height='16' rx='2'/><path d='m22 7-10 6L2 7'/>\",\n
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2. Filled solid icon. Add fill='black'. Add stroke='none' for crisp edges / sharp corners (small triangles, chevrons, arrow tips, pixel-precise cutouts); keep the template stroke when you want visual weight matching line icons.

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  chevron-down:   \"<path fill='black' stroke='none' d='M12 15.5l-7-7 2-2 5 5 5-5 2 2z'/>\",\n
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3. Compass / ring-with-inner-element. Outlined ring + filled inner element(s).

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  play-button:    \"<circle cx='12' cy='12' r='10'/><polygon fill='black' points='7.5 6 17.5 12 7.5 18'/>\",\n
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4. Filled disc with a punched symbol (the circle-* family). Filled r=10 disc centered at (12,12), symbol cut out via fill-rule='evenodd' + stroke='none'. The symbol MUST be a single continuous closed polygon (or non-overlapping subpaths) — overlapping subpaths push the winding count odd and re-fill the cutout. When in doubt, look up a shipped circle-* icon and trace from its geometry.

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  circle-plus:    \"<path stroke='none' fill='black' fill-rule='evenodd' d='M2 12A10 10 0 1 0 22 12A10 10 0 1 0 2 12ZM10.5 6 13.5 6 13.5 10.5 18 10.5 18 13.5 13.5 13.5 13.5 18 10.5 18 10.5 13.5 6 13.5 6 10.5 10.5 10.5Z'/>\",\n
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Critical mask-image constraints

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Non-negotiable consequences of mask-image rendering:

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  1. No fill/stroke color contrast. Both are opaque. Traditional outlining isn't possible — only geometric outline tricks (negative-space halo via evenodd, or a hollow stroked shape with no fill).
    2. \n
  2. Filled shape + stroke = bigger filled shape. The 2px stroke adds ~1 unit of opacity in every direction. Inset a polygon by 1 unit to keep its visible size when it carries the template stroke.
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  3. A transparent gap is required to \"outline\" anything. Shape B is only visible against filled shape A if B is outside A, a cutout in A (evenodd), or both.
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  4. stroke-linejoin='round' rounds every sharp corner by ~1 unit. Use stroke='none' for true sharp corners.
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  5. ViewBox edges clip. A path at x=24 with a 2px stroke renders to x=25 and gets clipped. Pull paths in by 1 unit to preserve perimeter stroke. (The circle-* family can use a full r=10 disc only because it uses stroke='none'.)
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  6. Masks can't occlude — no \"in front / behind\". Overlapping shapes merge into one blob. Fanned decks, stacked cards, \"one shape behind another\" do NOT work — use distinct, spatially-separated elements.
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  7. Stroke eats the gap between elements. Each stroked shape extends half its stroke-width toward its neighbor. Budget ~4 geometric units of gap for ~2.5 visual units when spacing composites.
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  8. SVG transform renders fine in the mask (e.g. transform='rotate(angle cx cy)') — but re-read #6 before overlapping.
    9. \n
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Reference docs (mounted at @cerb-docs, read-only)

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You have the full Cerb documentation mounted. Read these instead of guessing — especially before claiming an icon does or doesn't exist.

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PathWhat it gives you
@cerb-docs/references/docs/developers/icons.mdThe canonical icon list. Every registered icon name in the shipped set, plus why an icon is a single-color mask that inherits currentColor. Check here first for naming conventions and prior art (circle-*, logo-*, chart-*, window-*, move-* families).
@cerb-docs/references/docs/setup/developers/icon-builder.mdThe Icon Builder: it holds inner geometry only, the wrapper <svg> is fixed by the icon pipeline, and output is two source lines (the $icons entry in cerb-icons.scss + the name entry in the UI service). Nothing is saved server-side.
@cerb-docs/references/docs/data-queries/ui/icons.mdtype:ui.icons data query — filterable/pageable list of icon names, the same source behind the icon-listing tool and the in-app pickers.
@cerb-docs/references/docs/toolbars.mdHow icon: is consumed on toolbar buttons and menu links (icon in addition to, or instead of, a label).
@cerb-docs/references/docs/sheets.mdThe icon column type and the icon:/icon_at: parameters on card, link, interaction, and button columns — the other main place icons render.
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Practical notes that follow from those pages:

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Draft, look, refine -- do not try to one-shot it

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cerb_set_geometry pushes a revision and the preview updates immediately, so you can SEE the icon. That makes a rough first pass cheap and a long analytical build expensive. Get something on screen in your first turn or two, then adjust.

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Working approach

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  1. Start from Lucide. Most icons map to an existing Lucide design — adapt rather than invent. Lucide path data drops in cleanly after converting double quotes to single quotes.
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  2. Pick a pattern family up front and design within its constraints.
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  3. If an evenodd cutout fills in solid, check the winding at its center — for a disc + symbol, the symbol's center must be winding 2 (transparent). That is the diagnosis for that symptom, not a step to run before every draft.
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  4. Take multi-icon requests one at a time. An icon editor holds a single icon's geometry, so work through a set in sequence — settle one glyph, note its shared parameters (stroke weight, corner radius, optical size), and carry them into the next so the family stays consistent.
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  5. Iterate on dimensions, not approach. \"Fatter / thinner / shorter / deeper\" → adjust existing parameters. \"Different style entirely\" → switch pattern family.
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  6. Round to 2 decimals max unless precision matters (e.g. cutout sagitta math).
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  7. Use your scratch area when a shape genuinely needs it — traced path data, winding and sagitta math, intermediate geometry held across steps. Prefer looking at the preview over computing what it would have looked like.
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