Create Theme

Configuration Location

Themes are configured in ~/.config/sidecar/config.json:

{
  "ui": {
    "showFooter": true,
    "showClock": true,
    "nerdFontsEnabled": false,
    "theme": {
      "name": "default",
      "overrides": {
        "primary": "#FF5500",
        "success": "#00FF00"
      }
    }
  }
}

Available Base Themes

Sidecar ships with 21 modern, contrast-compliant themes designed around a 7-step neutral ramp and single signature chrome accent:

• sidecar-modern - Modern default with signature gold accent (#c0982f) and dark neutral ramp
• catppuccin-mocha - Soothing lavender/blue (#89b4fa) with dark mantle
• tokyonight-storm - Tokyo neon night blue (#7aa2f7)
• gruvbox-dark - Retro warm gold (#fabd2f) & aqua (#8ec07c)
• dracula - Refined vampire violet (#bd93f9)
• nord - Arctic frost cyan (#88c0d0)
• atom-one-dark - Balanced editor cyan/blue (#61afef)
• kanagawa-wave - Woodblock print wave blue (#7e9cd8)
• rose-pine - Soho rose (#eb6f92) & pine cyan (#9ccfd8)
• everforest-dark - Earthy forest green (#a7c080) & warm amber (#dbbc7f)
• solarized-dark - Precision amber/yellow (#b58900) & cyan (#2aa198)
• monokai-pro - Crisp gold (#ffd866) & green (#a6e22e)
• night-owl - Deep navy blue (#82aaff)
• ayu-mirage - Warm sunset gold (#6dcbfa) on slate
• github-dark - Crisp GitHub cobalt (#58a6ff)
• synthwave - 80s retrowave fuchsia (#ff77ff)
• cobalt2 - High-contrast Wes Bos cobalt yellow (#ffe50a)
• horizon - Cyberpunk apricot/red (#ed718e)
• shades-of-purple - High-contrast magenta/violet (#ff77ff)
• spacegray-eighties - Muted classic warm gray & blue (#7ba1cf)
• zenburn - Low-contrast soft green (#90cbae)

Creating a Custom Theme

Method 1: Override Specific Colors

Start from a base theme and override specific colors:

{
  "ui": {
    "theme": {
      "name": "default",
      "overrides": {
        "primary": "#E91E63",
        "success": "#4CAF50",
        "error": "#F44336",
        "syntaxTheme": "github"
      }
    }
  }
}

Method 2: Full Theme Override

Override all colors for complete control. See references/palette-reference.md for every available color key and their default values across themes.

Method 3: Custom Gradient Borders

Panel borders support angled gradients (default 30 degrees) flowing diagonally:

{
  "ui": {
    "theme": {
      "overrides": {
        "gradientBorderActive": ["#FF0000", "#FF7F00", "#FFFF00", "#00FF00", "#0000FF", "#8B00FF"],
        "gradientBorderAngle": 45
      }
    }
  }
}

Gradients support 2+ color stops. If not specified, solid borderActive/borderNormal colors are fallback.

Tab Styles

Configure with tabStyle and tabColors in overrides:

Tab Styles:

• gradient - Colors flow continuously across all tabs (per-character interpolation)
• per-tab - Each tab gets a distinct solid color from array (cycles)
• solid - Uses theme primary/tertiary colors
• minimal - No background, active tab uses underline

Built-in Presets (use as tabStyle value):

• rainbow - Red -> Green -> Blue -> Purple (gradient)
• sunset - Orange -> Peach -> Pink (gradient)
• ocean - Deep Blue -> Cyan -> Light Blue (gradient)
• aurora - Purple -> Dark Purple -> Teal (gradient)
• neon - Magenta -> Cyan -> Green (gradient)
• fire - Red-Orange -> Orange -> Gold (gradient)
• forest - Dark Green -> Mid Green -> Light Green (gradient)
• candy - Pink -> Purple -> Turquoise (gradient)
• pastel - Pink, Green, Blue, Yellow (per-tab)
• jewel - Ruby, Sapphire, Amethyst, Topaz (per-tab)
• terminal - Red, Green, Cyan, Yellow (per-tab)
• mono - Theme primary color (solid)
• accent - Theme accent color (solid)
• underline - No background, underlined active (minimal)
• dim - No background, dim inactive (minimal)

Examples:

// Use a preset
{ "overrides": { "tabStyle": "sunset" } }

// Custom gradient
{ "overrides": { "tabStyle": "gradient", "tabColors": ["#FF6B35", "#F7C59F", "#FF006E"] } }

// Per-tab distinct colors
{ "overrides": { "tabStyle": "per-tab", "tabColors": ["#FF5555", "#50FA7B", "#8BE9FD", "#F1FA8C"] } }

Color Key Categories

All colors use hex format (#RRGGBB). Key categories:

• Brand: primary, secondary, accent
• Status: success, warning, error, info
• Text: textPrimary, textSecondary, textMuted, textSubtle, textHighlight, textSelection, textInverse
• Background: bgPrimary, bgSecondary, bgTertiary, bgOverlay, selectionBg
• Border: borderNormal, borderActive, borderMuted
• Gradient border: gradientBorderActive, gradientBorderNormal (arrays), gradientBorderAngle (number)
• Tab: tabStyle, tabColors (array)
• Diff: diffAddFg, diffAddBg, diffRemoveFg, diffRemoveBg
• UI elements: buttonHover, tabTextInactive, link, toastSuccessText, toastErrorText
• Danger: dangerLight, dangerDark, dangerBright, dangerHover
• Blame age: blameAge1 through blameAge5
• Third-party: syntaxTheme (Chroma theme name), markdownTheme (dark/light)

Full color values for all themes: see references/palette-reference.md.

Syntax Themes

The syntaxTheme value can be any Chroma theme:

• monokai, dracula, github, github-dark, nord, onedark, solarized-dark, solarized-light, vs, vim

See Chroma Style Gallery for all options.

It applies everywhere Sidecar highlights code: raw file previews, git diffs, and fenced code blocks inside rendered Markdown. If the name is not a registered Chroma style, Sidecar falls back deterministically to github for light palettes and monokai for dark ones rather than failing.

Markdown Colors

There is no Markdown-specific color family. Rendered Markdown — Files preview, Notes view mode, conversation bodies, workspace document/issue/resource panes, release notes — is styled by internal/markdown from the same normalized semantic palette every other surface uses, so a new theme gets palette-correct Markdown for free and a live theme preview (#) repaints already-open documents immediately.

The rendered document deliberately paints no background so pane chrome and selection keep owning the canvas; only inline code and the Chroma code-block style carry one.

markdownTheme

markdownTheme is not a color. It has two behaviors:

• dark or light — the normal case. Sidecar takes only structure from that Glamour preset (margins, prefixes, list glyphs, task markers) and then overwrites every color from the table above. Set it to match your background; if it is missing or unusable, Sidecar picks a mode from bgPrimary's luma.
• Any other value — an advanced full-style override: a registered Glamour style name, or a path to a Glamour JSON style file. That file owns the whole Markdown appearance and the palette mapping is skipped entirely. Use this only when you deliberately want Markdown to stop tracking the Sidecar palette.

Curated themes and community conversions must use dark or light; an all-theme audit test (internal/markdown/theme_audit_test.go) fails on a missing semantic color, an unknown syntaxTheme, or a non-structural markdownTheme.

Color Validation

Colors must be valid hex in #RRGGBB format. Invalid colors are ignored.

• Valid: "#FF5500", "#ff5500" (lowercase ok)
• Invalid: "FF5500" (missing #), "#F50" (shorthand), "red" (named colors)

Nerd Fonts

When nerdFontsEnabled is true: pill-shaped tabs (Powerline chars), pill-shaped buttons. Requires a Nerd Font installed in your terminal.

Community Themes

Press # to open theme switcher, then Tab to browse 601 community color schemes. Supports search, live preview, color swatches. Press Enter to save.

Community themes are converted from iTerm2 color schemes. Stored by scheme name:

{
  "ui": {
    "theme": {
      "name": "default",
      "community": "Catppuccin Mocha",
      "overrides": { "primary": "#ff79c6" }
    }
  }
}

To regenerate community themes from upstream:

git clone https://github.com/mbadolato/iTerm2-Color-Schemes ~/code/iTerm2-Color-Schemes
./scripts/generate-schemes.sh [path-to-repo]

Per-Project Themes

Each project can have its own theme. When switching with @, theme changes automatically.

{
  "projects": {
    "list": [
      { "name": "api", "path": "~/code/api", "theme": { "name": "dracula" } },
      { "name": "web", "path": "~/code/web", "theme": { "name": "default", "community": "Catppuccin Mocha" } },
      { "name": "tools", "path": "~/code/tools" }
    ]
  }
}

Set per-project: press #, then ctrl+s to toggle scope to "Set for this project".

Resolution order: project theme > global ui.theme > "sidecar-modern".

Programmatic Theme Registration

import "github.com/marcus/sidecar/internal/styles"

myTheme := styles.Theme{
    Name:        "my-theme",
    DisplayName: "My Custom Theme",
    Colors: styles.ColorPalette{
        Primary:   "#FF5500",
        Secondary: "#00FF55",
        // ... all other colors
    },
}

styles.RegisterTheme(myTheme)
styles.ApplyTheme("my-theme")

API Reference

styles.ListThemes()                    // []string of available theme names
styles.GetTheme("dracula")             // Theme struct
styles.IsValidTheme("my-theme")        // bool
styles.IsValidHexColor("#FF5500")       // bool
styles.GetCurrentTheme()               // Theme
styles.GetCurrentThemeName()           // string
styles.ApplyTheme("dracula")
styles.ApplyThemeWithOverrides("default", map[string]string{"primary": "#FF5500"})

// Resolve effective theme for a project path (project > global > default)
import "github.com/marcus/sidecar/internal/theme"
resolved := theme.ResolveTheme(cfg, "/path/to/project")
theme.ApplyResolved(resolved)

Modern Theme Architecture (Sidecar Modern Standard)

Modern Sidecar themes (sidecar-modern, catppuccin-mocha) follow a refined, disciplined design system:

1. Single Chrome Accent: Exactly one primary accent hue (e.g. Gold #c0982f in sidecar-modern, Blue #89b4fa in catppuccin-mocha). Used for cursor ❯, active tab highlight, footer key glyphs (keyHintFg), and active border. Chrome does not use multi-color rainbow gradients.
2. Structural Neutral Ramp: Geometry and hierarchy are carried by neutral lightness steps, not saturation:
   • BgPrimary: Canvas background
   • BgSecondary: Header / footer bar fills
   • BgTertiary: Selected row background
   • SelectionBg: Text-selection highlight; must lift off the canvas (TargetSelectionSeparation, currently 2.65:1) without leaving the canvas ink pole
   • SurfaceRaised: Raised pills (key hints, bar chips) sitting subtly above canvas/bars
   • BorderNormal / BorderMuted: Rules and hairlines
   • TextPrimary → TextSecondary → TextMuted → TextSubtle: Typography ramp
3. Tab Style: Default to "minimal" with single accent underline/highlight.
4. Semantics-Driven Colors: Colors other than the single chrome accent are strictly earned by meaning (Done = Green, Open/ID = Teal, Destructive/Error = Red, Warning/P2 = Yellow/Gold, Links/Headings = Blue/Sapphire).

Contrast Rules (Strict AA Standard)

When authoring or converting themes, check contrast against all surfaces:

1. Multi-Fill Validation (>= 4.5:1):
   • TextPrimary, TextSecondary, TextMuted, and TextSelection must clear 4.5:1 on ALL three background fills: BgPrimary, BgSecondary, and BgTertiary (selected row).
   • All semantic accents (Primary, Secondary, Success, Warning, Error, Info, Link, LaneWorking, LaneBlocked, LaneDone, LaneIdle, LanePaused, ProjectHues[*]) must clear >= 4.5:1 on BgPrimary, BgSecondary, and BgTertiary.
2. Raised Chrome (SurfaceRaised):
   • TextPrimary, TextSecondary, TextMuted, and KeyHintFg must clear >= 4.5:1 on SurfaceRaised.
   • TextSubtle and TabTextInactive must clear >= 3.0:1 on SurfaceRaised.
3. Ink on Bright Fills:
   • For bright or pastel status/danger backgrounds (e.g. DangerBright, ToastSuccess, ToastError), use dark canvas ink (#0f1113 or #181825) for TextInverse / Toast*Text, as white (#ffffff) fails contrast on light reds/yellows.
   • DangerLight must clear >= 4.5:1 on DangerDark.
4. Text-selection highlight (SelectionBg):
   • Must clear TargetSelectionSeparation (currently 2.65:1) against BgPrimary so a selected span is findable against the shell canvas. BgTertiary (the selected-row fill) is not enough. Bump that constant to lift every theme at once.
   • Must stay on the same ink pole as BgPrimary, and TextPrimary must still clear >= 4.5:1 on it. Do not invert selected text or lighten the highlight until headings and syntax wash out.
   • NormalizePalette lifts empty, inverted, or too-dim values; author the role deliberately on curated themes.