Custom Color Theme

SkimDown lets you define and switch between custom color themes for the preview area. Themes are written as JSON or JSONC files in the VS Code color theme format, so existing VS Code theme assets can be reused.

Where themes live

Drop JSON or JSONC files into:

~/Library/Application Support/SkimDown/Themes/

Open the folder quickly from the app via View → Theme → Open Themes Folder.

JSON format

Each file is a standalone VS Code color theme. Comments and trailing commas used by VS Code theme files are accepted. For example, save this as solarized-light.json:

{
  "$schema": "vscode://schemas/color-theme",
  "name": "Solarized Light",
  "type": "light",
  "colors": {
    "editor.background": "#fdf6e3",
    "editor.foreground": "#586e75",
    "descriptionForeground": "#93a1a1",
    "panel.border": "#eee8d5",
    "editorGroupHeader.tabsBackground": "#eee8d5",
    "editorWidget.background": "#fdf6e3",
    "textLink.foreground": "#268bd2",
    "editor.findMatchHighlightBackground": "#f8e8a5",
    "editor.findMatchBackground": "#fad880"
  }
}

• name — the label shown in View → Theme. Falls back to the file name when omitted.
• type — "light" or "dark". Picks the light/dark code highlight CSS and the Mermaid theme.
• colors — VS Code color keys. Only a small set is used by SkimDown; the rest are ignored.

tokenColors (syntax highlighting) is not yet supported. Code blocks use GitHub's light or dark highlight palette based on type.

Color key mapping

When multiple keys are listed, SkimDown uses the first key found in the theme.

Preview element	VS Code color keys
Background	editor.background
Text	editor.foreground, foreground
Secondary text	descriptionForeground, disabledForeground
Borders	panel.border, editorGroup.border, editorWidget.border, contrastBorder
Subtle backgrounds	editorGroupHeader.tabsBackground, editor.lineHighlightBackground, sideBar.background
Panel backgrounds	editorWidget.background, editor.background
Links and accents	textLink.foreground, editorLink.activeForeground, focusBorder
Search highlights	editor.findMatchHighlightBackground
Current search match	editor.findMatchBackground

Missing keys fall back to SkimDown's built-in light or dark palette based on the theme type.

Reloading themes

The Themes folder is not watched automatically. After adding or editing a JSON or JSONC file, choose View → Theme → Reload Themes to refresh the list.

If the theme currently in use is deleted, SkimDown falls back to the System theme on the next reload or launch.