Published: October 8, 2025
Last updated: April 20, 2026
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Create custom themes that users can select in their settings.

Configuration

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frontend:
  styling:
    customThemes:
      default:
        description: "The default theme"
        css: ""                    # empty = built-in styling; or path to a CSS file
      dark-blue:
        description: "Dark Blue"
        css: "dark-blue.css"
      corporate:
        description: "Corporate Theme"
        css: "corporate.css"

How Themes Work

  1. Define themes in customThemes map (key = theme ID)
  2. Users select theme in Settings → Profile
  3. Selected theme CSS is injected into HTML:
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<style>
  {{ .htmlVars.userSelectedTheme }}
</style>

Theme Structure

Each theme requires:

  • Key: Unique theme identifier (used internally)
  • description: Display name shown to users
  • css: Path to CSS file, or "" for the built-in look (typical for the default entry)
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customThemes:
  theme-id:                        # Key (unique identifier)
    description: "Theme Name"      # Display name
    css: "path/to/theme.css"       # CSS file path

Default Theme

Theme with key "default" is automatically applied to all logged-in users:

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customThemes:
  default:
    description: "Company Theme"
    css: "company-theme.css"

This overrides the default styling for all users who haven’t selected a different theme.

Creating Themes

“Reduced Rounded Corners” Theme

You can view the included by default theme here on github to see how it works.

You can also override variables provided by filebrowser:

TEXT 
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    /* Basic Styles */
    :root {
      --background: {{ .htmlVars.lightBackground }};
      --alt-background: #ddd;
      --surfacePrimary: gray;
      --surfaceSecondary: lightgray;
      --textPrimary: #546e7a;
      --textSecondary: gray;
      --iconBackground: #dddddd;
      --activeWhiteIcon: gray;
    }
    .dark-mode {
      --background: {{ .htmlVars.darkBackground }};
      --alt-background: #283136;
      --surfacePrimary: #20292F;
      --surfaceSecondary: #3A4147;
      --divider: rgba(255, 255, 255, 0.12);
      --textPrimary: rgba(255, 255, 255, 0.87);
      --textSecondary: rgba(255, 255, 255, 0.6);
      --iconBackground: #1e1f20;
      --activeWhiteIcon: white;
    }

Minimal Theme

minimal.css:

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/* Simplified interface */
.card {
  box-shadow: none;
  border: 1px solid #e0e0e0;
}

.btn {
  border-radius: 2px;
}

Complete Example

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frontend:
  styling:
    customThemes:
      default:
        description: "Standard"
        css: "standard.css"
      high-contrast:
        description: "High Contrast"
        css: "high-contrast.css"
      minimal:
        description: "Minimal"
        css: "minimal.css"
      dark-blue:
        description: "Dark Blue"
        css: "dark-blue.css"

User Experience

Users see themes in Settings:

  1. Go to Settings → Profile
  2. Select theme from dropdown
  3. Theme applies immediately
  4. Selection persists across sessions

Theme Precedence

CSS is applied in this order (later overrides earlier):

  1. Base application styles
  2. customCSS (applies to all users)
  3. Background colors (lightBackground, darkBackground)
  4. User-selected theme (userSelectedTheme)

Use CSS variables: Makes themes more maintainable

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/* In theme CSS */
:root {
  --primary: #0066cc;
  --secondary: #ff6600;
}

.btn-primary {
  background: var(--primary);
}

Combining with Custom CSS

Both customCSS and themes can be used together:

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frontend:
  styling:
    customCSS: "base-corporate.css"  # Applied to all users
    customThemes:
      default:
        description: "Light"
        css: "light-variant.css"     # User choice
      dark:
        description: "Dark"
        css: "dark-variant.css"      # User choice

Next Steps