SEO: Too Much Contrast? SEO Doesn't Always Care

This is Post 2 from my “Accessible Links & SEO” series — based on the paper I presented at SIU 2025. If you missed Part 1 (about unique links being punished by bots), you might want to check it out. Now let’s talk contrast — and what happens when you're just… too accessible? Quick Setup We know accessibility matters. We know WCAG 2.0 suggests a minimum contrast ratio of 4.5:1 for readable links. So naturally, I expected better contrast to mean better SEO ranking. I built a labeled dataset using real-world shopping websites, gathered link features like contrast ratio (contrast_ratio), and paired them with SERP positions from both Google and Bing. Then this happened: Higher contrast didn’t improve ranking. Sometimes, it even correlated negatively. Let me rephrase that: I had links with perfect, 12:1 contrast. And they ranked lower than links with 6:1. Data Snapshot: Feature: contrast_ratio Average contrast (ranked): 12.04 Average contrast (not ranked): 12.43 So the higher contrast group actually performed worse in visibility terms. It wasn’t huge — but it was consistent across both search engines. What gives? Here are two thoughts: Accessibility isn’t the only game in town. Search engines likely weigh link context, site architecture, crawlability, internal references, etc. High contrast alone isn’t enough to signal value. Overengineering for bots ≠ better visibility. You might pass every Lighthouse audit, and still get ghosted by Google. Bonus Visual: Here’s the ranking distribution against contrast ratio: (This is where you could insert a simple contrast histogram or scatter plot — let me know if you want one generated.)

Jun 28, 2025 - 01:40

SEO: Too Much Contrast? SEO Doesn't Always Care

This is Post 2 from my “Accessible Links & SEO” series — based on the paper I presented at SIU 2025.

If you missed Part 1 (about unique links being punished by bots), you might want to check it out.

Now let’s talk contrast — and what happens when you're just… too accessible?

Quick Setup

We know accessibility matters.

We know WCAG 2.0 suggests a minimum contrast ratio of 4.5:1 for readable links.

So naturally, I expected better contrast to mean better SEO ranking.

I built a labeled dataset using real-world shopping websites, gathered link features like contrast ratio (contrast_ratio), and paired them with SERP positions from both Google and Bing.

Then this happened:

Higher contrast didn’t improve ranking.

Sometimes, it even correlated negatively.

Let me rephrase that:

I had links with perfect, 12:1 contrast.

And they ranked lower than links with 6:1.

Data Snapshot:

Feature: contrast_ratio

Average contrast (ranked): 12.04

Average contrast (not ranked): 12.43

So the higher contrast group actually performed worse in visibility terms.

It wasn’t huge — but it was consistent across both search engines.

What gives?

Here are two thoughts:

Accessibility isn’t the only game in town.

Search engines likely weigh link context, site architecture, crawlability, internal references, etc.

High contrast alone isn’t enough to signal value.
Overengineering for bots ≠ better visibility.

You might pass every Lighthouse audit, and still get ghosted by Google.

Bonus Visual:

Here’s the ranking distribution against contrast ratio:

(This is where you could insert a simple contrast histogram or scatter plot — let me know if you want one generated.)