fix(dark-palette): improve base colors

[liamdebeasi]

Issue number: resolves #29219

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What is the current behavior?

We got feedback that the current dark theme is a bit jarring when compared with native. In particular, devs are expecting the contrast to be white for many of these colors to match native iOS. Currently, text inside of a primary button is black on dark mode, but devs expect it to be white. Additionally, the dark mode colors appear to be too washed out when compared with their light mode counterparts.

The team discussed this and we think we can find a way to make the colors more in line with what devs expect while still allowing for AA color contrast levels.

What is the new behavior?

• Adjusted the secondary and danger colors to be slightly more vibrant/inline with what developers expect in mobile apps while still meeting AA color contrast.

Does this introduce a breaking change?

• Yes
• No

Other information

I intentionally did not change the contrast color, and I intentionally did not significantly change the vibrancy of each color token. I did some research into how the native platforms handle colors. I'll place this information here, because there are some subtle differences between web and native that make a difference.

Material Design

Source

Material Design 2 calls for desaturated color tokens as well as flipping contrast colors. For example, a vibrant purple background with light text on light mode is a washed purple with dark text on dark mode. The colors in Ionic <=7 did not follow these patterns. The tokens in Ionic 8 now follows these patterns, so what we have in main means we are aligning closer with native MD than have in the past.

iOS

Source

iOS is a bit tricky. On the docs, Apple references the WCAG color contrast formula (what Ionic follows). However, the table they present below is slightly different:

Text Size	Text Weight	Minimum Contrast Ratio
Up to 17 points	All	4.5:1
18 points and larger	All	3:1
All	Bold	3:1

The last row is the main difference. WCAG states that text that is bold AND >=14pts (~18.66px) needs to meet a minimum contrast ratio of 3:1. Apple's guidelines state that any text that is bold (regardless of size) needs to meet a minimum contrast ratio of 3:1. In other words, Apple is using different guidelines to choose colors which is why colored dark mode buttons on iOS typically use white text.

However, Apple is inconsistent in implementing its own guidelines. Consider the following red buttons in the Apple Music app.

Screenshot	Meets Web guidelines	Meets Apple guidelines	Notes
	❌	❌	Text is not bold which makes it not meet either guidelines.
	❌	✅	Text is bold which makes it pass the Apple guidelines, but it's still too small to also pass the Web guidelines.

Ionic

One of the things I tried is adjusting the base color to work well with white and black backgrounds. It's common to have a blue background with white text (such as a button) AND to have a blue link on a black background (such as an a element). This approach does not work well for the shade/tint colors used for hover/focus states. These colors also need to meet Web guidelines.

Consider the following example:

Screenshot	Notes	Text/Link passes AA guidelines	Tint passes AA guidelines
	This uses the same primary color found in the light palette	❌	✅
	This changes the base color such that the Text/Link passes with a 4.5:1 ratio	✅	❌
	This changes the base color such that the Tint passes with a 4:5:1 ratio	❌	✅

We also considered adjusting the a and ion-text colors to use the tint color. We decided against that because it a) felt a little odd given that tint is typically used for states (hover, focus, etc) and b) we were concerned that making this change would impose future restrictions on how this color palette can evolve.

Conclusion

While Ionic's colors don't exactly match the iOS colors, the reality is that we are a web-based tool, so we are going to be evaluated using web-based tools/standards. As a result, it's recommended that we align closer with the Web guidelines than Apple's guidelines.

Testing

Testing:

Developers can look at the colors by opening http://localhost:3333/src/themes/test/colors

In the video below, the first state is the dark theme in main. The second state is the proposed changes.

Visual Comparison
comparison.mov

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