Feature Request: Support for Per-Style font-features Configuration

[ThorstenRhau]

Description:

I would like to request support for defining OpenType font-features on a per-style basis within the Ghostty configuration. Currently, the font-features setting applies globally to all font styles (to the best of my understanding), which limits granular control when different stylistic sets are needed for specific styles like italic or bold italic.

Use Case:

My specific use case involves applying different stylistic sets to various font styles:

Italic Font: Enable ss06 stylistic set
Bold Italic Font: Enable ss07 stylistic set
This level of control would be especially beneficial for users working with fonts that support extensive OpenType features, allowing for more refined typographic customization in ghostty.

Proposed Configuration Example:

Ideally, the configuration could support something like this:

font-family = "YourRegularFont"
font-features = "ss01"  # Global feature (optional)

font-family-italic = "YourItalicFont"
font-features-italic = "ss06"  # Apply only to italic

font-family-bold-italic = "YourBoldItalicFont"
font-features-bold-italic = "ss07"  # Apply only to bold italic

Benefits:

Provides granular control over typography, enhancing the visual appeal and legibility of terminal content.
Aligns with advanced font customization workflows, particularly for users who rely on OpenType features.
Reduces the need for workarounds like creating custom font files with pre-applied stylistic sets.

Thank you for considering this request, and I appreciate the excellent work on Ghostty!