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Caesium is a cursive typeface for programming, derived from Cascadia Code. While it inherits some of Cascadia’s structure, Caesium takes a more radical approach in design.

Downloads

Font files are available in the exported folder. You can download the latest archive of the repo from the release page.

Design

Glyph categories vary:

• Lowercase letters: cursive with a 2° slant.
• Uppercase letters: roman with a 1° slant.
• Symbols and digits: upright.

This gives Caesium rhythm, lends characters a script-like feel, and improves legibility.

Cursiveness

By default, Caesium doesn’t fully adopt cursive forms. For example, ⟨a⟩ and ⟨g⟩ are two-storey (or maybe 1.5-storey?), which gives letters unique shapes and improves the differentiation between similar characters.

With the OpenType feature ss01 enabled, or by default in italic subfamilies (though they can hardly be called orthodox italics), more letters become cursive. The OpenType feature ss02 can be used to revert cursive italics, as well as making ⟨z⟩ more distinguishable from ⟨3⟩.

Submono

Another attractive feature is “submono”: letters inside a word adjust their width and position, while the total width of the word remains unchanged. This allows letters that should have been wide, like ⟨W⟩ and ⟨m⟩, to be relaxed and those should have been narrow, like ⟨I⟩ and ⟨t⟩, to be tightened, resulting in more proportional glyphs.

This feature, nominally embodied by kern, is not implemented by altering the advance width of each glyph, but by replacing the shape of glyph face to create a visual shift. Therefore, it won’t break the display where strict monospaced glyphs are required.

Weight Mapping

Caesium’s default weight (Regular) is lighter than Cascadia’s; it aligns better with other fonts. To replicate Cascadia’s original Regular weight, use Caesium Thick.

Coding Ligatures

The author is not a fan of coding ligatures, so Caesium doesn’t include them. However, for consistency with digits, ⟨x⟩ and ⟨b⟩ turn into roman forms when part of integer literals.

Misc Optimization

• Enlarged, dot‑like punctuation.
• Curved commas and quotation marks.
• Dashed zeros (including super/subscripts).

Character Coverage

• Adobe Latin 2.
• Adobe Greek 1.
• Box drawings.
• Block elements.
• Fish git prompt symbols.
• Recrafted arrows and keyboard symbols.

Demo in Use

<br>(This theme is called Aqua.)

Fallback and Pairing

It’s recommended to use the original Cascadia as a fallback for Latin/Cyrillic/Arabic characters, and 方正巴龙草书黑体 for Han.

License

Caesium is distributed under the SIL Open Font License 1.1. The names “Caesium” and “Cascadia” are reserved font names. See the LICENSE file for details.