The author provides an history about the base, reset ,normalize and classless stylesheets.

The page itself is a demo of base.css, a classless stylesheet, and document itself.

Each topic is covered by a description, the rules and the relying css implementation. Each rule is well meant for accessibility such as "You should read a caption without having to scrol". It starts with the CSS Properties.

Use CSS properties for customization. There is the root style rules:

1. Set customization options on the the root element for all elements
2. Use native properties for font family and font size options.a
3. For font size, CSS has font relative units to create variations from the root or parent value.
4. For font family, it's useless to use custom property. Its value, a string value, can't create variations. Variation of font family would be by, if possible, using font variant alternates. a
5. Use custom property for line height. This maintains unitless value while creating automatic variations for blocks. b
6. Use custom property for pseudo content. This enables fallback trick for its native counterpart. c
7. Use custom property for the others due to lack of native properties. d
8. Prevent adjustments of font size orientation changes in iOS
9. Remove padding and margin, use box model of border box, and inherit color and font on all elements.

The library defines carefully the font-family, font-size, line-height, line-length, color, styles, blocks, mixes and phrases.

A font family declaration is a set of typefaces to create safer designs. Using multiple typefaces requires a sound knowledge of type pairings: space, type (sans, serif, cursive), wight, width, style normal and italic, cases: smalls, caps and smapp caps, roles: caption, body and display.

Font-sizes are defined with the em unit and relative calculations based on a --font-scale value.

The line height is computed based on the element around it. For example the paragraph following a hgroup with a heading. It creates a cohesive design.
All line height are derived from a --line-height value.

To respect the support of dark and light mode, developers must use the light-dark() function. Prefer human-based color mdoels such as LCH or OKLCH. The primary color component is Hue. Lightness and Chroma creates variations. Variations for one hue is a monochromatic pallete; for 2 hues is diadic; for 3 hues is triadic; and so on. CSS can programmatically create a live pallete from one hue using calc(). A 90deg deviation creates a complementary scheme; a type of diadic.

The web is filled with unsemantic styles: the absence of styles, the misuse of styles, the lack of unique styles. This can be seen through the lens of base stylesheets, as of writing.
All components — blocks, mixes, and phrases of media and forms — should have unique styles.

Blocks define region in the HTML document. Subsections uses one _ for each nesting level.

Mixes use all-round borders to define the boundary of their content

Phrases is all about content and forms. They are inline content, so their block content is maintained within a line height. Each phrase is clearly identified