Wikipedia is a marvel. It is the Library of Alexandria of our time, a meticulously curated repository of human knowledge, wrapped in a user interface so ruthlessly utilitarian it makes a hospital corridor look like a rave.

But sometimes, when I am deep in a Wikipedia rabbit hole reading about List of animals with fraudulent diplomas at 2:00 AM, the sterile white background feels... insufficient. I don't want brutalist minimalism. I want the web the way the ancients intended: dripping in neon pink, plastered in Comic Sans, and crawling with pixelated cats.

So, I decided to write a custom Wikipedia User Script to turn the site into a 1998 GeoCities cyberpunk fever dream.

Instead of writing this from scratch, I wanted to see how well modern LLMs could handle writing niche MediaWiki API scripts. Here is a field report on how I built this abomination using Gemini 3.1 Pro Preview.

Grounding Gemini with Wikipedia-specific syntax

LLMs are great at writing vanilla JavaScript, but Wikipedia user scripts rely on specific, slightly archaic MediaWiki globals (like mw.loader.using and mw.util.addCSS). If you just blindly ask an LLM to "make Wikipedia pink," it usually hallucinates browser extensions or generic Tampermonkey scripts.

To bypass this, I jumped into Google AI Studio and loaded up the Gemini 3.1 Pro Preview model.

The secret sauce here was using the URL Context feature. I toggled URL Context on and pasted in the URL for Wikipedia's custom scripting documentation:
https://en.wikipedia.org/wiki/Wikipedia:User_scripts

My prompt was simple but unhinged:

"Using the provided documentation on Wikipedia User Scripts, write a script for my Special:MyPage/common.js that makes my Wikipedia viewing experience look like a 90s cyberpunk GeoCities page. I want a pink/cyan grid background, glowing Comic Sans headers, a massive scrolling <marquee> for the article title, a giant glowing sparkle mouse trail, and a squad of animated cats walking across the top of my screen."

Because Gemini 3.1 Pro Preview had the actual documentation in its context window, it knew exactly how to inject CSS securely via MediaWiki's utility functions, and it gave me a plug-and-play script.

Breaking down the script

The resulting script is a beautiful combination of modern DOM manipulation and deeply offensive 90s aesthetics.

1. The Marquee Title

If we are going to read about the Emu War, that title needs to move. The script grabs the #firstHeading element and violently wraps its inner HTML in a <marquee> tag.

var $title = $('#firstHeading');
var titleText = $title.html();
$title.html('<marquee scrollamount="15" behavior="alternate">' + titleText + '</marquee>');

Note: The fact that modern browsers in 2026 still parse and execute the <marquee> tag is a testament to the web’s unbreakable backwards compatibility. It is the digital equivalent of a vestigial tail.

2. The Sparkle Trail (A Lesson in Throttling)

To create the mouse trail, the script listens to the mousemove event and appends absolutely-positioned <span> elements containing cyberpunk symbols (✦, ★, ✨) to the DOM.

To prevent this from immediately melting my GPU (a very real threat when generating hundreds of DOM nodes a second), the model smartly implemented a timestamp throttle:

var now = Date.now();
if (now - lastSparkleTime < 40) return; // Only spawn a sparkle every 40ms
lastSparkleTime = now;

It then applies a CSS @keyframes animation to each sparkle so they slowly drift downward, rotate 180 degrees, and fade to opacity: 0 before being garbage-collected by a setTimeout a second later.

3. The Mathematics of Walking Cats

Instead of using a clunky JS setInterval to move the cats, Gemini 3.1 leaned into pure, hardware-accelerated CSS animations.

It created a fixed header container (pointer-events: none so I can still click the search bar through the cats' ethereal bodies). Then, it applied two separate animations.

The first animation slides the whole squad from 100vw (off-screen right) to -100% (off-screen left).

The second animation creates the "walking" illusion. If you think about the geometry of a walking pixel cat, it's essentially a sine wave. To achieve this, the script applies a 10px vertical bounce to each cat (transform: translateY(-10px)).

To make it look like a chaotic squad rather than a synchronized military parade, the script uses the nth-child(even) pseudo-class to offset the animation delay of every other cat:

.walking-cat {
    animation: catBounce 0.4s alternate infinite ease-in-out;
}
.walking-cat:nth-child(even) {
    animation-delay: 0.2s; /* Phase offset for the bounce! */
}

We are essentially phase-shifting the vertical oscillation of our felines to simulate independent locomotion.

The final results

I pasted the code into my Special:MyPage/common.js, hit publish, and bypassed my cache.

The result is staggering.

I am currently reading the deeply serious, heavily cited Wikipedia article for Maximilien Robespierre. The background is a dark void overlaid with a neon pink laser grid. The header "MAXIMILIEN ROBESPIERRE" is glowing in hot pink Comic Sans, aggressively bouncing off the edges of my monitor.

Every time I move my mouse to hover over a citation, a massive explosion of 45-pixel-wide cyan stars erupts across the text. And above it all, a squad of five neon cats marches endlessly toward the left side of my screen, oblivious to the Reign of Terror occurring in the text below them.

It is awful. I am never turning it off.

If you want to ruin your own Wikipedia experience, you can find the complete script in the replies below. Just remember to log in, navigate to Special:MyPage/common.js and Special:MyPage/common.css, and let the 90s flow through you.

StackFeed

Vandalizing My Own Wikipedia Experience: A 90s Cyberpunk GeoCities Makeover