First you'll need to place selected themes in your `themes` directory (i.e `~/.config/helix/themes`), the directory might have to be created beforehand.
To use a custom theme add `theme = <name>` to your [`config.toml`](./configuration.md) or override it during runtime using `:theme <name>`.
The default theme.toml can be found [here](https://github.com/helix-editor/helix/blob/master/theme.toml), and user submitted themes [here](https://github.com/helix-editor/helix/blob/master/runtime/themes).
First create a file with the name of your theme as file name (i.e `mytheme.toml`) and place it in your `themes` directory (i.e `~/.config/helix/themes`).
Each line in the theme file is specified as below:
where `key` represents what you want to style, `fg` specifies the foreground color, `bg` the background color, and `modifiers` is a list of style modifiers. `bg` and `modifiers` can be omitted to defer to the defaults.
To specify only the foreground color:
```toml
key = "#ffffff"
```
if the key contains a dot `'.'`, it must be quoted to prevent it being parsed as a [dotted key](https://toml.io/en/v1.0.0#keys).
These keys match [tree-sitter scopes](https://tree-sitter.github.io/tree-sitter/syntax-highlighting#theme). We half-follow the common scopes from [macromates language grammars](https://macromates.com/manual/en/language_grammars) with some differences.
For a given highlight produced, styling will be determined based on the longest matching theme key. So it's enough to provide function to highlight `function.macro` and `function.builtin` as well, but you can use more specific scopes to highlight specific cases differently.
