This pull request makes several improvements to the site's typography and font weight management. The main changes include introducing new CSS variables for font weights, refining font sizing and line-height settings, and standardizing font-family usage across the base and reset stylesheets.

Typography and font weight improvements:

• Added new CSS variables for font weights (--weight-light, --weight-regular, --weight-semibold) in base.css and applied them to headings and links for more consistent styling.
• Updated heading (h1-h6) styles to use responsive font sizes and appropriate font weights, improving readability and hierarchy.

Font sizing and line-height refinements:

• Set a base font size of 1.125rem (18px) on the html element in base.css for better default sizing.
• In reset.css, replaced the previous combined font shorthand with separate properties for font-size, font-family, and line-height for clarity and maintainability.

Font-family standardization:

• Ensured consistent usage of system-ui, sans-serif as the font stack in both base and reset stylesheets.