Increase font legibility by removing the font-weight declaration

## Issue Description

I don't know if I'm getting old or if macOS has changed its font rendering, but I now find it difficult to read the text on an H2 post. The font weight is too low.

Removing the `font-weight` declaration from the `body` element resets its weight to `400`, making the text much more legible but still very Human Made.

## Steps to reproduce:

Squint at an H2 post.

## Expected Result:

I can read it.