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Rules Book

<p>Flex is a fluid icon family inspired by nature's curves. It replaces rigid geometry with smooth, flowing forms. The Line variant features elegant strokes with organic curves.</p>

Flex Line

**Summary**: Flex's most refined sub-style — 1px continuously curving organic stroke on a 14px grid, the most visually elegant line icon available, suited to consumer and lifestyle products where icons should feel modern and naturally fluid. Flowing nature-inspired paths communicate organic forms rather than systematic grids. The tone signals refined motion: "we are in flow." Best for health, wellness, and lifestyle apps where organic visual language mirrors product values; personal finance and fintech wanting a human register; and creative tools where visual craft matters; best deployed at 24px+ where the organic curve quality is fully visible.

**Last updated**: 2026-04-23

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## Fit & Recommendation

### Primary use cases

- Consumer products where the visual language should feel modern and naturally elegant
- Health, wellness, and lifestyle apps where organic visual language mirrors product values
- Personal finance and fintech products that want to feel human and approachable
- Creative and design-adjacent tools where visual craft matters
- Products with generous spacing and large icon display sizes (24px+)
- Navigation where icons should complement illustration or photography, not compete

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## Brand & Cultural Identity

### What it communicates

> "We are refined and in motion."

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## Visual & Technical Specs

### Visual properties

| Property | Value |
|----------|-------|
| Stroke weight | 1px |
| Fill | None |
| Corner treatment | Smooth fluid curves throughout — no geometric corners anywhere |
| Color | Monochrome |

### Emotional Scores

Flex Line is one of the warmer sub-styles in the catalog — organic flowing curves create warmth, though the 1px weight and cool monochrome colour slightly offset this. It is among the softest sub-styles in the catalog — the 1px stroke with continuously flowing curves is among the softest line constructions possible. It is one of the friendlier sub-styles in the catalog — organic curves lean friendly, with the refined thinness of the stroke pulling slightly toward elegance. It is one of the more playful sub-styles in the catalog in a considered way — flowing organic curves are fluid and refined rather than casual, sitting on the friendlier side of the midpoint. On its human↔mechanical character, it is one of the most human-feeling sub-styles in the catalog — nature-inspired curves communicate flowing organic forms, not systematic grids.

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## Pairing & Compatibility

### Typography pairing

- **Primary**: Plus Jakarta Sans — humanist warmth with subtle stroke contrast; shares the organic flowing quality
- **Alternative**: Outfit — clean humanist, modern; flowing curves sit naturally alongside
- **Editorial**: Libre Baskerville Light — for lifestyle contexts, serif stroke contrast echoes organic curve variation
- **Body**: Inter Regular — universal readable body, steps back to let Flex Line lead
- **Avoid**: IBM Plex Sans, Neue Haas Grotesk, cold monolinear grotesque — perfectly constructed geometric letters fight the organic language


<p>Flex is a fluid icon family inspired by nature’s curves. It favors smooth, flowing forms. More organic than Core and subtler than the chunky Plump. Read about the <a href="https://blog.streamlinehq.com/flex/" rel="noopener noreferrer" target="_blank">design process</a>.</p>

Fluid icons

Business Office

Rules Book icon - Flex Line Set

Download Rules Book SVG vector or transparent PNG icon in Line, Stroke style(s) for Sketch and Figma. It belongs to Flex Line vectors SVG collection.