[Accessibility] Used text color should have enough contrast with background

[Ionaru]

When text is placed on a background that does not provide enough contrast with the text, that text becomes difficult to read or impossible to some.

Some of the deno_doc output does not provide enough contrast to meet the WCAG Level AA requirement of 4.5:1.

For example the Function & Method symbols on their backgrounds:

Text color: #056cf0
Background color: #dae9fd

A slightly darker color like #1b61dc would pass the requirement: https://contrast-finder.tanaguru.com/result.html?foreground=%23056CF0&background=%23DAE9FD&ratio=4.5&isBackgroundTested=false&algo=Rgb&distanceSort=asc

However with the current tailwind generation logic, setting another text color would probably also affect the background color.

Other sections that I found to have lacking contrast:

• The Class symbol
• The Variable symbol (also in dark mode)
• The Interface symbol (also in dark mode)
• documentNavigation links
• symbolSubtitle, like "extends"
• The word "Class"

There's maybe more, but I haven't seen all of the possible documentation.

More info: https://www.w3.org/TR/WCAG22/#contrast-minimum & https://www.w3.org/WAI/WCAG22/Understanding/contrast-minimum.html