# css-border-gradient

Applies refined gradient border treatments to cards, modals, and buttons in CSS or Tailwind. Useful when surfaces need subtle edge highlights without loud glowing outlines.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 1500 installs · ★ 7001
- Author: MengTo
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/MengTo/Skills/tree/HEAD/agent-skills/web-design/css-border-gradient/SKILL.md
- Updated: 2026-10-25
- HTML: https://affpapa.org/en/nevibecode/skills/css-border-gradient

## What it does

The skill provides CSS snippets and design guidelines for delicate borders on interface components. Instead of flat borders or intense neon glows, the agent builds quiet edge highlights at 135deg or 160deg angles. The standard border width is 1px; 2px is reserved for large hero panels or active states. Stop opacity stays below 0.4 so the border frames the content without overpowering it.

Three implementation techniques are included. The standard pattern combines two `linear-gradient` layers with `padding-box` and `border-box` alongside a transparent border. When an element already has a complex background image, a masked pseudo-element with `mask-composite: exclude` preserves the underlying graphics. A Tailwind shortcut also maps the properties into arbitrary utility classes.

The same alpha value rarely works for both light and dark themes. Contrast shifts between color modes, so border stops require separate tuning for dark and light surfaces.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add MengTo/Skills --skill css-border-gradient -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/css-border-gradient/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/css-border-gradient/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add MengTo/Skills --skill css-border-gradient -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/css-border-gradient/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add MengTo/Skills --skill css-border-gradient -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/css-border-gradient/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install MengTo/Skills css-border-gradient
```

2. **Manually: put the files in place**
- File: `.github/skills/css-border-gradient/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add MengTo/Skills --skill css-border-gradient -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/MengTo/Skills --path agent-skills/web-design/css-border-gradient
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/css-border-gradient/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add MengTo/Skills --skill css-border-gradient -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/MengTo/Skills/tree/HEAD/agent-skills/web-design/css-border-gradient/SKILL.md

## When to use it
- Highlight pricing cards with a subtle gradient edge
- Render a gradient border over complex backgrounds using CSS masks
- Construct Tailwind arbitrary utility classes for border highlights
- Style active tabs or focused buttons without loud glow effects

## Example prompts
- Create a 1px subtle gradient border for a pricing card with a brand accent.
- Add a masked pseudo-element border to a modal without overwriting its background.
- Convert this gradient border treatment into Tailwind arbitrary utility classes.

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: a8712ba5222238c7.

BEGIN THIRD-PARTY FILE a8712ba5222238c7
````text
---
name: css-border-gradient
description: Apply subtle gradient-border treatments for premium web surfaces. Use when cards, pricing panels, nav bars, modals, buttons, or hero surfaces need a refined edge highlight without a loud glow.
---

# Border Gradients

## Use When
- A surface needs a more premium edge than a flat `border`.
- Dark glass, pricing, hero, modal, or feature-card UI feels too plain.
- A hover or focus state needs a quiet brand accent.

## Defaults
- Width: `1px`; use `2px` only for large hero cards or active states.
- Radius: inherit the parent radius.
- Angle: `135deg` or `160deg`.
- Stops: neutral highlight, one brand accent, neutral fade.
- Opacity: keep most stops below `0.4`; subtle beats shiny.

## Simple CSS Pattern
Use this when the surface has a solid or translucent fill.

```css
.gradient-border {
  --surface: rgba(10, 14, 24, 0.72);
  --border-a: rgba(255, 255, 255, 0.34);
  --border-b: rgba(125, 92, 255, 0.36);
  --border-c: rgba(255, 255, 255, 0.08);

  border: 1px solid transparent;
  border-radius: 20px;
  background:
    linear-gradient(var(--surface), var(--surface)) padding-box,
    linear-gradient(135deg, var(--border-a), var(--border-b), var(--border-c)) border-box;
}
```

```html
<div class="gradient-border">
  ...
</div>
```

## Masked Pattern
Use this when the surface already has a complex background that should not be overwritten.

```css
.gradient-border-mask {
  position: relative;
  border-radius: 20px;
}

.gradient-border-mask::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  padding: 1px;
  background: linear-gradient(
    145deg,
    rgba(255, 255, 255, 0.34),
    rgba(125, 92, 255, 0.36) 45%,
    rgba(255, 255, 255, 0.08)
  );
  -webkit-mask:
    linear-gradient(#fff 0 0) content-box,
    linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
}
```

## Tailwind Shortcut
Use arbitrary properties for one-off surfaces.

```html
<div class="rounded-2xl border border-transparent [background:linear-gradient(rgba(10,14,24,.72),rgba(10,14,24,.72))_padding-box,linear-gradient(135deg,rgba(255,255,255,.34),rgba(125,92,255,.36),rgba(255,255,255,.08))_border-box]">
  ...
</div>
```

## Taste Rules
- Apply to one hierarchy level at a time: primary card, active tab, selected plan, or hero panel.
- Do not use rainbow borders, full-saturation neon, or animated gradients by default.
- Keep the border quieter than the content. It should frame, not compete.
- Pair with restrained depth: a soft shadow or inner highlight is enough.
- Check light and dark themes separately; the same alpha rarely works for both.
````
END THIRD-PARTY FILE a8712ba5222238c7

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