> ## Documentation Index
> Fetch the complete documentation index at: https://tty7.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Fonts

> The bundled default, fallback chains, ligatures, and why CJK needs a word.

**Settings → Appearance → Typography** covers the everyday choices; the rest is
`config.json`.

| Setting                         | Default |                                               |
| ------------------------------- | ------- | --------------------------------------------- |
| **Font family**                 | Hack    | Picked from fonts installed on your system    |
| **Font size**                   | 15 px   | The terminal grid                             |
| **Interface font size**         | 16 px   | Everything outside the grid (12–24)           |
| **Line height**                 | 1.4     | A multiple of the font size                   |
| **Bold font** / **Italic font** | —       | Distinct faces, when you want them            |
| **Font ligatures**              | off     | Contextual alternates stay off unless you ask |

## Hack is bundled

The default font ships inside the binary. It renders identically on every
machine without relying on a system install, so a fresh laptop looks like the
one you set up last year.

## Fallbacks

`font_family` is the primary face; `font_fallbacks` is an ordered list tried in
turn for anything the primary lacks.

```json theme={null}
{
  "font_family": "JetBrains Mono",
  "font_fallbacks": ["Maple Mono NF CN", "PingFang SC", "Apple Color Emoji"]
}
```

Leave `font_fallbacks` out and you get the platform's default chain:

|             | Default fallbacks, in order                                                         |
| ----------- | ----------------------------------------------------------------------------------- |
| **macOS**   | Menlo · Hasklug Nerd Font Mono · Maple Mono NF CN · PingFang SC · Apple Color Emoji |
| **Windows** | Maple Mono NF CN · Cascadia Mono · Microsoft YaHei · Segoe UI Emoji                 |
| **Linux**   | Maple Mono NF CN · DejaVu Sans Mono · Noto Sans CJK SC · Noto Color Emoji           |

Each ends in faces the host OS actually ships, and those stock names are
appended to whatever list you write yourself — so a `config.json` copied from
another platform still resolves.

## OpenType features

`font_features` passes tags straight through to the shaper:

```json theme={null}
{
  "font_features": { "calt": true, "liga": 1, "ss01": true, "zero": false }
}
```

A tag must be four alphanumeric characters; `true`/`false` map to `1`/`0`.
Anything malformed is skipped with a log line rather than failing the whole
config.

## CJK and the two-column grid

<Info>
  A cell is one advance of the primary face, and a wide (CJK) character is
  pinned to exactly two of them. A CJK fallback sits flush in its slot only if
  its ideographs advance **twice** the primary's Latin advance.
</Info>

Bundled Hack advances 0.60205em, so a two-column slot is 1.2041em — while every
stock CJK face (Microsoft YaHei, PingFang SC, Noto Sans CJK) advances 1.0em.
Those glyphs get left-aligned in the slot, leaving a \~0.2em gap on the right of
every character.

[Maple Mono NF CN](https://github.com/subframe7536/maple-font) is in every
platform's default chain for exactly this reason: 0.6em Latin, 1.2em CJK, an
exact two-cell fit against Hack. It leads the chain on Windows and Linux, and on
macOS sits behind Menlo and Hasklug, which cover Latin and Nerd Font glyphs
first. It is referenced by name only, never bundled (\~20 MB per weight) —
install it and tty7 picks it up with no config change.

If you want CJK set *tight* rather than merely even, change the **primary** face
instead. One that advances 0.5em — Sarasa Mono SC, say — makes two columns
exactly 1.0em.