Tailwind CSS 3.4: dynamic viewports, :has(), and subgrid

Tailwind 3.4 arrived just before the bigger architectural jump of v4, but it was already pointing in the same direction: closer to the platform, less plugin ceremony, and stronger support for real-world layout work.

The release highlights are dynamic viewport units, `:has()` support, balanced text wrapping, subgrid, better spacing and selector ergonomics, and more direct access to newer browser capabilities from utility classes.

For design-system teams, this was a high-value release because it reduced the number of places where custom CSS still had to step in for common responsive and editorial patterns.