css-border-gradient

Installation

$npx skills add guilhermemarketing/esc-skills --skill css-border-gradient

Summary

Apply a pseudo-element masking technique to render gradient borders on any element. The agent can generate and customize the .border-gradient snippet with specific angles, colors, thickness, and radius values.

SKILL.MD

name: css-border-gradient description: Create and apply CSS gradient borders using a pseudo-element mask (the .border-gradient::before technique), including Tailwind-friendly usage and customization of angle, colors, border thickness, and radius. Use when asked for gradient borders, border glow, or the specific mask-composite border gradient snippet.

CSS Border Gradient Skill

Workflow

  1. Confirm environment (plain CSS vs Tailwind) and gather missing specs (border radius, thickness, angle, colors).
  2. Provide the baseline snippet and a short usage checklist.
  3. Offer focused tweaks only (change angle, colors, thickness, radius) and avoid redesigning the component.

Baseline snippet

.border-gradient {
  position: relative;
}

.border-gradient::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 10px;
  padding: 1px;
  -webkit-mask: linear-gradient(#fff 0 0) content-box,
    linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  background: linear-gradient(225deg,
    rgba(255, 255, 255, 0.0) 0%,
    rgba(255, 255, 255, 0.2) 50%,
    rgba(255, 255, 255, 0.0) 100%);
  pointer-events: none;
}

Usage checklist

  • Insert the snippet in global CSS or the page <head>.
  • Add border-gradient to the element.
  • Remove any existing border styles.
  • Match the element radius to the pseudo-element radius.

Tailwind example

<div class="border-gradient rounded-lg before:rounded-lg">
  ...
</div>

If a project uses Tailwind layers, wrap the class in @layer utilities.

Customization knobs

  • Thickness: change padding (for example 2px).
  • Radius: change border-radius or the before:rounded-* class.
  • Angle: change the linear-gradient(225deg, ...) angle.
  • Colors: adjust the rgba(...) stops to fit the theme.

Common pitfalls

  • Mismatched radius between the element and pseudo-element.
  • Leaving an existing border on the element (double border).
  • Tailwind purge removing the class because it is not referenced in content files.

Questions to ask when specs are missing

  • What border radius and thickness do you want?
  • What gradient angle and colors should it use?
  • Is this for light, dark, or both themes?