RFR: 8367321: Fix CSS bugs in dark theme [v2]

[Hannes Wallnöfer]

> Please review a change to fix various problems with the recently introduced dark theme for API docs:
> 
>  - Minimizes flickering when page is loaded with dark theme ([before](https://download.java.net/java/early_access/jdk26/docs/api/allclasses-index.html) / [after](https://cr.openjdk.org/~hannesw/8366942/api.00/allclasses-index.html))
>  - Fixes link color in table captions of inherited member summaries and class use pages ([before](https://download.java.net/java/early_access/jdk26/docs/api/java.base/java/lang/Exception.html#method-summary) / [after](https://cr.openjdk.org/~hannesw/8366942/api.00/java.base/java/lang/Exception.html#method-summary))
>  - Fixes section color in Serialized Form page ([before](https://download.java.net/java/early_access/jdk26/docs/api/serialized-form.html) / [after](https://cr.openjdk.org/~hannesw/8366942/api.00/serialized-form.html))
> 
> The change also includes some JS and CSS refactoring/cleanup. 
> 
> Generated documentation was tested on Firefox, Chrome and Safari and [can be viewed here](https://cr.openjdk.org/~hannesw/8366942/api.00/java.base/module-summary.html) (module java.base only).

Hannes Wallnöfer has updated the pull request incrementally with one additional commit since the last revision:

  Adjust table colors

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27191/files
  - new: https://git.openjdk.org/jdk/pull/27191/files/7fe07bd4..9f457997

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27191&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27191&range=00-01

  Stats: 10 lines in 1 file changed: 0 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/27191.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27191/head:pull/27191

PR: https://git.openjdk.org/jdk/pull/27191