Splitting Into Files

Your ocean theme works. It builds, it looks great, everything lives in one file. That’s fine for a small theme, but as your design grows, a single file gets unwieldy. Let’s fix that.

The Import System

Sassy lets you split your theme across multiple files using config.import. Each import path is resolved relative to the main theme file.

Here’s the idea: extract your palette and vars into shared files, and keep the main theme file focused on structure.

ocean.yaml (trimmed down):

config:
  name: "Ocean"
  type: dark
  import:
    - "./shared/palette.yaml"
    - "./shared/variables.yaml"

theme:
  colors:
    editor.background: $(std.bg)
    editor.foreground: $(std.fg)
    editorCursor.foreground: $(accent)
    sideBar.background: $(std.bg.panel)
    activityBar.background: $(std.bg.panel)

  tokenColors:
    - name: Comments
      scope: comment
      settings:
        foreground: $(scope.comment)
    - name: Keywords
      scope: keyword
      settings:
        foreground: $(scope.keyword)
    - name: Strings
      scope: string
      settings:
        foreground: $(scope.string)

shared/palette.yaml:

palette:
  cyan: "#4a9eff"
  white: "#e0e0e0"
  green: "#a8d8a8"

shared/variables.yaml:

vars:
  accent: $$cyan
  main: $$white

  std:
    fg: $(main)
    bg: "#1a1a2e"
    bg.panel: lighten($(std.bg), 15)

  scope:
    comment: fade($(std.fg), 60)
    keyword: $(accent)
    string: $$green

Build it the same way you always have:

npx @gesslar/sassy build ocean.yaml

The output is identical. The organisation is just better.

How Merging Works

When Sassy processes imports, it follows two rules:

1. Objects deep-merge. If both the imported file and the main file define vars.std.bg (or palette.cyan), the main file’s value wins. Later values override earlier ones at every nesting level.

2. Arrays append. If both files define tokenColors, the imported entries come first, followed by the main file’s entries. Nothing gets replaced — both sets appear in the output. Applying these as fallbacks to whatever is missing or not covered by the imports.

This means you can define a base set of tokenColors in a shared file, then add theme-specific rules in the main file. They all end up in the final output, in order, with the first matching rule winning.

Import Order Matters

You can import multiple files:

config:
  import:
    - "./shared/palette.yaml"
    - "./shared/tokens.yaml"

They are processed in order. If both files define vars.accent, the second file’s value wins. Then the main theme file gets the final say over everything.

Think of it as layers: each import paints over the previous one, and the main file paints over all of them.

Next Steps

Now that your variables live in their own file, you can build a proper design system around them. That’s exactly what we’ll do next.