Themes

Highlights.jl includes over 360 color themes from the Gogh project.

Listing Themes

using Highlights

themes = Highlights.available_themes()
println(length(themes))

Popular Themes

Some commonly used themes include:

• Dracula - Dark theme with purple accents
• Nord - Arctic, north-bluish color palette
• Monokai Dark - Classic dark theme
• Gruvbox Dark - Retro groove colors
• One Dark - Atom-inspired dark theme
• Solarized Dark - Precision colors for dark backgrounds
• Tokyo Night - Dark theme inspired by Tokyo lights
• Catppuccin Mocha - Soothing pastel theme

Theme Selection

Themes are specified by exact name (case-sensitive):

highlight(code, :julia, "Dracula")
highlight(code, :julia, "Nord")

Fuzzy Matching

If you mistype a theme name, Highlights.jl suggests similar themes based on edit distance:

highlight(code, :julia, "darcula")
# ERROR: Theme 'darcula' not found. Similar themes:
#   - Dracula
#   - ...

highlight(code, :julia, "monokai")
# ERROR: Theme 'monokai' not found. Similar themes:
#   - Monokai Dark
#   - Monokai Pro
#   - ...

Theme Colors

Each theme provides:

• 16 ANSI colors (used for syntax highlighting)
• Background color
• Foreground color

The syntax highlighting maps TreeSitter captures to these colors based on token type (keywords, strings, comments, etc.).

Custom Themes

Create custom themes by deriving from existing themes:

# Override specific colors (2 = keywords)
custom = Theme("Dracula", colors = Dict(2 => "#ff0000"))
highlight(code, :julia, custom)

# Change background
Theme("Nord", background = "#1a1a1a")

# Give it a new name
Theme("Dracula", name = "MyDracula", colors = Dict(2 => "#ff0000"))

# Chain derivations
base = Theme("Dracula", background = "#1a1a1a")
custom = Theme(base, colors = Dict(3 => "#00ff00"))

Per-Capture Styling

Themes can attach text styling — :bold, :italic, :underline — to tree-sitter captures via the styles keyword. A bare Symbol or a Vector of Symbols is accepted:

Theme("Dracula", styles = Dict(
    "comment"  => :italic,
    "keyword"  => :bold,
    "function" => [:bold, :italic],
    "type"     => :underline,
))

Lookup walks the capture hierarchy, so setting "keyword" covers "keyword.return", "keyword.function", etc.

Gogh themes ship without styling — set it explicitly when you derive your own. Styles work in every output format: ANSI, HTML (inline and class-based), LaTeX, and Typst.

Removing Styling

Styles use override semantics during derivation (matching colors). To remove a style inherited from a base, set the capture to an empty Vector:

italic_comments = Theme("Dracula", styles = Dict("comment" => :italic))
no_style        = Theme(italic_comments, styles = Dict("comment" => Symbol[]))

LaTeX and Underline

If any capture uses :underline, the LaTeX output uses \\uline from the ulem package. The generated stylesheet (Highlights.stylesheet for MIME("text/latex")) includes \\usepackage[normalem]{ulem} automatically. For inline LaTeX output, add the package to your document preamble.

Loading from JSON Files

Load themes from external JSON files (Gogh-compatible format):

highlight(code, :julia, "/path/to/theme.json")

# Or derive from a file
custom = Theme("/path/to/theme.json", colors = Dict(2 => "#ff0000"))

File-based themes are not cached, allowing live editing.

JSON Format

{
  "name": "MyTheme",
  "background": "#282A36",
  "foreground": "#F8F8F2",
  "color_01": "#262626",
  "color_02": "#E64747",
  "color_03": "#42E66C",
  "color_04": "#E4F34A",
  "color_05": "#9B6BDF",
  "color_06": "#E356A7",
  "color_07": "#75D7EC",
  "color_08": "#F8F8F2",
  "color_09": "#7A7A7A",
  "color_10": "#FF5555",
  "color_11": "#50FA7B",
  "color_12": "#F1FA8C",
  "color_13": "#BD93F9",
  "color_14": "#FF79C6",
  "color_15": "#8BE9FD",
  "color_16": "#F9F9FB"
}

Required: name. Optional: background, foreground, color_01-color_16.

JSON theme files carry colors only — to attach per-capture styling, load the file and derive: Theme("/path/to/theme.json", styles = …).

Color Indices

The 16 colors map to syntax elements: