About

Distinguishing paragraphs visually reduces misreading risk in long documents, lecture notes, or legal contracts. A wall of uniform text causes skipping errors at rates up to 15% per page in proofreading studies. This tool assigns a distinct background color to each paragraph using one of four algorithms: sequential palette cycling, pseudo-random distribution, two-color alternation, or HSL gradient interpolation between user-defined endpoints. It operates on plain text split by blank-line delimiters. The output is copyable rich HTML or exportable as a standalone .html file. Note: color contrast is not guaranteed for arbitrary palettes - verify readability against WCAG AA (4.5:1 ratio) if the output is intended for accessibility-sensitive contexts.

Formulas

In Gradient mode, intermediate colors are computed via HSL interpolation. For n paragraphs between start color C₀ and end color C₁:

H_i = H₀ + in − 1 ⋅ (H₁ − H₀)

The same linear interpolation applies to S (saturation) and L (lightness) channels independently. Where i is the paragraph index (0-based), H₀, S₀, L₀ are the HSL components of the start color, and H₁, S₁, L₁ are those of the end color.

In Sequential mode, paragraph i receives palette color at index:

colorIndex = i mod paletteSize

In Random mode, the palette array is shuffled using Fisher-Yates algorithm, then cycled sequentially through the shuffled order. In Alternating mode, only the first two palette colors are used, toggling on parity of i.

Reference Data

Color Mode	Algorithm	Best Use Case	Min. Palette Size
Sequential	Cycle through palette in order, wrap at end	Structured documents, numbered sections	2
Random	Fisher-Yates shuffle of palette per batch	Creative writing, visual variety	3
Alternating	Two-color toggle (even/odd index)	Contracts, comparison text, zebra-striping	2
Gradient	HSL interpolation between two endpoints	Progress narratives, timeline documents	2 (endpoints)
Common Pastel Palettes
Soft Rainbow	#FFB3BA, #FFDFBA, #FFFFBA, #BAFFC9, #BAE1FF, #E8BAFF
Ocean Breeze	#B5EAD7, #C7CEEA, #E2F0CB, #FFDAC1, #FF9AA2
Warm Sunset	#FDCB82, #F8A978, #F48B94, #D98BB5, #B48BCC
Cool Mint	#D4F1F4, #B8E6E6, #96D9D6, #75C9C8, #54B9B9
Earth Tones	#E6CCB2, #DDB892, #B08968, #C4A77D, #D4C5A9
Berry Mix	#F0C6D0, #E0A8C8, #D08CC0, #C070B8, #B054B0
Lemon Fields	#FFF9C4, #FFF59D, #FFF176, #FFEE58, #FFEB3B
Forest	#C8E6C9, #A5D6A7, #81C784, #66BB6A, #4CAF50
Lavender Dream	#E8D5F5, #D4B8E8, #C09BDB, #AC7ECE, #9861C1
Coral Reef	#FECDD3, #FDA4AF, #FB7185, #F43F5E, #E11D48

Frequently Asked Questions

By default, paragraphs are separated by one or more blank lines (double newline \n\n). You can toggle to single-newline mode, where every line break creates a new paragraph. Leading and trailing whitespace within each paragraph is preserved but empty paragraphs (containing only whitespace) are discarded.

In Sequential mode, colors wrap around using modulo arithmetic. If you have 3 colors and 10 paragraphs, colors cycle as 1-2-3-1-2-3-1-2-3-1. In Random mode, the shuffled palette similarly wraps. In Gradient mode, intermediate steps are computed regardless of count, so all paragraphs receive unique interpolated colors. Alternating mode always uses exactly 2 colors.

Yes. The "Copy Rich Text" button copies HTML with inline background-color styles. Most email clients (Gmail, Outlook) and word processors (Google Docs, MS Word) preserve inline CSS background colors when pasting. Some clients may strip styles - in that case, use the HTML file export and import it.

The implementation interpolates through the shortest arc on the hue circle. If the start hue is 350° and the end hue is 10°, it interpolates through 360°/0° (a 20° arc) rather than the long way around (340° arc). This produces visually smooth gradients across the red boundary.

The tool uses dark text (#2D3748) on light pastel backgrounds. The built-in palettes are selected to maintain a contrast ratio above 4.5:1 against dark text. If you define custom colors, avoid high-saturation or low-lightness backgrounds. A lightness value (L in HSL) above 75% generally ensures readable dark text.

No hard limit is enforced. The tool has been tested with documents containing over 500 paragraphs without performance issues. DOM rendering is the bottleneck - above approximately 2000 paragraphs, initial render may take a noticeable moment. For very large documents, consider splitting the text.