Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add devinilabs/pro-skill --skill css-alpha-maskinggit clone --depth 1 https://github.com/devinilabs/pro-skillWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/devinilabs/pro-skill/css-alpha-masking)<a href="https://agentmods.dev/skills/devinilabs/pro-skill/css-alpha-masking"><img src="https://agentmods.dev/badge/skills/devinilabs/pro-skill/css-alpha-masking.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00042 | $0.00422 |
| Opus 5 | $0.00021 | $0.00211 |
| Sonnet 5 | $0.00008 | $0.00084 |
| Haiku 4.5 | $0.00004 | $0.00042 |
Grade A, and why
css-alpha-masking scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
100% identical to css-alpha-masking — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
What it actually says
CSS Alpha Masking Skill
Workflow
- Confirm direction (horizontal or vertical) and fade stop percentages.
- Provide the inline CSS snippet and any needed class usage.
- Offer small tweaks only (direction, stop positions, colors).
Usage checklist
- Apply the mask styles directly on the element or in a CSS class.
- Always include both
mask-imageand-webkit-mask-imagefor Safari. - Ensure the element has visible content; masks reveal/hide alpha only.
Horizontal (left/right) fade
/* Add this inline CSS to any element */
mask-image: linear-gradient(to right, transparent, black 15%, black 85%, transparent);
-webkit-mask-image: linear-gradient(to right, transparent, black 15%, black 85%, transparent);
Vertical (top/bottom) fade
/* Add this inline CSS to any element */
mask-image: linear-gradient(to bottom, transparent, black 15%, black 85%, transparent);
-webkit-mask-image: linear-gradient(to bottom, transparent, black 15%, black 85%, transparent);
Customization knobs
- Direction:
to right,to left,to bottom,to top. - Fade depth: adjust
15%and85%stops. - Strength: change
transparenttorgba(0,0,0,0.2)for softer fades.
Common pitfalls
- Forgetting the
-webkit-mask-imagefallback in Safari. - Expecting masks to work on elements with
overflow: hiddenbut no visible content behind.
Questions to ask when specs are missing
- Which direction should the fade go?
- How wide should the fade edges be?
- Is this for images, text, or a container background?
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 3d ago First seen · 45 lines · 42 tokens per session scan A 049241d4c086
css-alpha-masking is a skill published in the GitHub repository devinilabs/pro-skill (23 stars, last pushed 25d ago), licensed MIT. It adds 42 tokens to every session and 422 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to css-alpha-masking, differing in 0 lines, and is treated as a copy.
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