html-css-style-color-guide — GitHub Copilot rule: colors and setup
This rule guides color choices for HTML and CSS, from backgrounds and text to gradients. Use it when editing browser-facing styles and checking contrast.
.github/instructions/html-css-style-color-guide.instructions.mdWhat html-css-style-color-guide does
The rule applies to **/*.html, **/*.css, and **/*.js when creating or changing styles. It organizes a palette with the 60-30-10 split: primary color, secondary color, then accent. For backgrounds, it favors light cool shades and neutrals; gradients should stay within one color family.
For readable text, pair light backgrounds with dark neutrals, or dark backgrounds with near-white shades. Yellow text and light text on a light background are out. Low-contrast combinations should be avoided as well. Hot colors such as red, orange, and yellow are reserved for small accents or alerts, so they do not belong across large background areas.
What it helps with
- choose a background color for an HTML page
- distribute interface colors with the 60-30-10 rule
- avoid text that blends into its background
- style a gradient within one color family
Example prompts for the agent
- Update the background and text colors in
index.htmlusing this rule. - Check whether the button and card styles follow the 60-30-10 split.
- Revise the page header gradient to follow the rule's guidance.
How to install html-css-style-color-guide
Manually: put the files in place
.github/instructions/html-css-style-color-guide.instructions.mdThe applyTo field sets which files it applies to
Manually: put the files in place
.claude/rules/html-css-style-color-guide.mdThe paths frontmatter field limits the files: move applyTo from the source into paths
AGENTS.md
Codex reads AGENTS.md: paste the rule text there
Manually: put the files in place
.cursor/rules/html-css-style-color-guide.mdcFrontmatter: description, globs, alwaysApply. Move applyTo from the source into globs, or the rule will not attach on its own
Manually: put the files in place
.devin/rules/html-css-style-color-guide.mdManually: put the files in place
.clinerules/html-css-style-color-guide.mdStep by step, with commands for each platform: AGENTS.md vs CLAUDE.md: what they are and which one to use
Questions about html-css-style-color-guide
How do I install html-css-style-color-guide for GitHub Copilot?
Add the rule file to your project at .github/instructions/html-css-style-color-guide.instructions.md.
What does html-css-style-color-guide do?
It sets color guidance for HTML and CSS, covering backgrounds, text contrast, palette balance, and gradients.
Which colors does the rule reject for backgrounds?
It rules out hot colors, including red, orange, and yellow, along with pink, purple, and magenta. Light cool shades and neutral tones are recommended instead.
Source text
html-css-style-color-guide.instructions.md · MIT
--- description: 'Color usage guidelines and styling rules for HTML elements to ensure accessible, professional designs.' applyTo: '**/*.html, **/*.css, **/*.js' --- # HTML CSS Style Color Guide Follow these guidelines when updating or creating HTML/CSS styles for browser rendering. Color names represent the full spectrum of their respective hue ranges (e.g., "blue" includes navy, sky blue, etc.). ## Color Definitions - **Hot Colors**: Oranges, reds, and yellows - **Cool Colors**: Blues, greens, and purples - **Neutral Colors**: Grays and grayscale variations - **Binary Colors**: Black and white - **60-30-10 Rule** - **Primary Color**: Use 60% of the time (*cool or light color*) - **Secondary Color**: Use 30% of the time (*cool or light color*) - **Accent**: Use 10% of the time (*complementary hot color*) ## Color Usage Guidelines Balance the colors used by applying the **60-30-10 rule** to graphic design elements like backgrounds, buttons, cards, etc... ### Background Colors **Never Use:** - Purple or magenta - Red, orange, or yellow - Pink - Any hot color **Recommended:** - White or off-white - Light cool colors (e.g., light blues, light greens) - Subtle neutral tones - Light gradients with minimal color shift ### Text Colors **Never Use:** - Yellow (poor contrast and readability) - Pink - Pure white or light text on light backgrounds - Pure black or dark text on dark backgrounds **Recommended:** - Dark neutral colors (e.g., #1f2328, #24292f) - Near-black variations (#000000 to #333333) - Ensure background is a light color - Dark grays (#4d4d4d, #6c757d) - High-contrast combinations for accessibility - Near-white variations (#ffffff to #f0f2f3) - Ensure background is a dark color ### Colors to Avoid Unless explicitly required by design specifications or user request, avoid: - Bright purples and magentas - Bright pinks and neon colors - Highly saturated hot colors - Colors with low contrast ratios (fails WCAG accessibility standards) ### Colors to Use Sparingly **Hot Colors** (red, orange, yellow): - Reserve for critical alerts, warnings, or error messages - Use only when conveying urgency or importance - Limit to small accent areas rather than large sections - Consider alternatives like icons or bold text before using hot colors ## Gradients Apply gradients with subtle color transitions to maintain professional aesthetics. ### Best Practices - Keep color shifts minimal (e.g., #E6F2FF to #F5F7FA) - Use gradients within the same color family - Avoid combining hot and cool colors in a single gradient - Prefer linear gradients over radial for backgrounds ### Appropriate Use Cases - Background containers and sections - Button hover states and interactive elements - Drop shadows and depth effects - Header and navigation bars - Card components and panels ## Additional Resources - [Color Tool](https://civicactions.github.io/uswds-color-tool/) - [Government or Professional Color Standards](https://designsystem.digital.gov/design-tokens/color/overview/) - [UI Color Palette Best Practices](https://www.interaction-design.org/literature/article/ui-color-palette) - [Color Combination Resource](https://www.figma.com/resource-library/color-combinations/)
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