[Feature request] Improve table style of default theme

[meteorlxy]

Clear and concise description of the problem

Table style of either dark mode and light mode does not look good:

• The head row and the odd-rows background color has the same background color
• The code background color is too similar with the odd-rows background color in dark mode

See link: https://vuepress.vuejs.org/guide/page.html

Suggested solution

We'd better try to improve the style of tables. Maybe we can take github as reference:

Github is using the same background color as the page for the head and odd-rows. Currently we are using it for even-rows

Alternative

No response

Additional context

No response