Function named 

pub fn named(style: &str) -> Option<BoxChars>

Resolve a named style string to BoxChars.

Returns None for unknown style names — the caller falls back to a default. Mirrors render-border.ts:32-34:

const box = typeof node.style.borderStyle === 'string'
  ? cliBoxes[node.style.borderStyle]
  : node.style.borderStyle;