RFR: 8340203: Link color is hard to distinguish from text color in API documentation

[Chen Liang]

On Tue, 8 Oct 2024 14:28:44 GMT, Hannes Wallnöfer <hannesw at openjdk.org> wrote:

> Please review a CSS-only change to make it easier to recognize links in API documentation with the default stylesheet. 
> 
> This subtle change makes the link color a bit lighter and more saturated and normal text a bit darker. The new link color is `#437291` which is the same color used for links on [openjdk.org](https://openjdk.org/) and other OpenJDK sites. 
> 
> The table of contents and breadcrumb-navigation uses a slightly darker color closer to the original one, which works better with the gray background and the large amount of links.
> 
> The change also introduces CSS variables (aka custom properties) for the TOC colors which have been missing, and removes some redundant CSS rules for the TOC header.
> 
> I've uploaded API docs for `java.base` to compare the changes:
> 
> New colors: https://cr.openjdk.org/~hannesw/8340203/api.00/java.base/java/lang/Thread.html
> Old colors: https://download.java.net/java/early_access/jdk24/docs/api/java.base/java/lang/Thread.html

The contrast indeed has improved, especially for inlined non-code fonts.

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PR Review: https://git.openjdk.org/jdk/pull/21409#pullrequestreview-2354743752