# One slider for weight, one for swashes: inside Last Christmas Variable

Most variable fonts let you slide from thin to bold. Last Christmas Variable has a second slider that brings in the swashes, from none at all to every one.

By Måns Grebäck · Published 2026-11-09 · Source: https://mansgreback.com/journal/one-slider-for-weight-one-for-swashes-inside-last-christmas-variable

Tags: Behind the font, Variable fonts

## Key points

- A variable font is one file that can produce any weight between its lightest and heaviest version.
- Last Christmas Variable has a second slider, ALTS, that goes from plain letters at 0 to every swash at 20.
- The weight runs from Thin (100) to Black (900), so every weight in between is available.

A normal font file is one fixed style: Regular is Regular, Bold is Bold. A variable font is different. It is a single file that can produce every style between its lightest and its heaviest, controlled by a slider.

Last Christmas Variable has two sliders.

## Slider one: weight

The first works like most variable fonts. It runs from Thin at 100 to Black at 900. In between you are not limited to Light, Regular and Bold: any number works, so a headline can be exactly as heavy as the layout needs.

![Merry Christmas in Last Christmas Variable at Thin, Regular and Black](https://mansgreback.com/journal/media/lc-weight-axis-9a9aa274-2400.webp "Thin, Regular and Black, with the swash slider halfway.")

## Slider two: swashes

The second slider is called **ALTS**, and it is less common. At 0 you get the plain letters. As you move it up, more and more letters change into their swash forms, until at 20 every letter that has one is wearing it.

![Merry Christmas at five positions of the swash slider: 0, 5, 10, 15 and 20](https://mansgreback.com/journal/media/lc-alts-axis-6e649aee-2400.webp "The same words at five positions of the swash slider.")

So instead of choosing alternates one letter at a time, you can turn the decoration up or down for a whole line at once, and stop wherever it looks right.

## How a font can morph

The trick behind any variable font is that the designer draws a few versions of every letter, called masters, and the computer calculates everything in between. Last Christmas has five: Thin, Light, Regular, Bold and Black.

For that to work, every version of a letter must be built from the same points, in the same order. A thin *a* and a black *a* need exactly the same number of points, so each point can travel from its thin position to its black one. If one version has a single point more, the font cannot morph.

> This is also why the [AI Variable Font](https://aringtypeface.com/mans-tools/) plugin keeps every point of the original letter when it makes new weights: with matching points, the new masters can morph into each other.

## Try it on a website

On the web, both sliders are set with one line of CSS, and can even be animated:

```css
h1 {
  font-family: "Last Christmas Variable";
  font-variation-settings: "wght" 650, "ALTS" 12;
}
```

Font: https://mansgreback.com/product/last-christmas

## Questions

**Where can I use the swash slider?**
In web browsers it works fully, through CSS. Desktop apps differ in how they handle a second, custom slider, so test it in yours first.

**Do I need the variable font if I have the normal one?**
No. The normal fonts contain the same letters and alternates. The variable one adds the freedom to choose any weight, and the slider.

## Fonts in this article

- https://mansgreback.com/product/last-christmas