Theme Customization

Custom CSS (Starter+)

Add custom CSS via PUT /blogs/:id with theme_config.customCss:

{
  "theme_config": {
    "customCss": "body { font-family: 'Georgia', serif; } h1 { color: #1a1a2e; }"
  }
}

Or use Dashboard → Settings → Theme → Custom CSS.

Caution

For security, the following are stripped: @import, expression(), url(javascript:), behavior, -moz-binding.

Header & Footer HTML (Creator+)

{
  "theme_config": {
    "headerHtml": "<nav><a href='/'>Home</a> | <a href='/about'>About</a></nav>",
    "footerHtml": "<footer>&copy; 2026 My Blog</footer>"
  }
}

Caution

<script> tags, on* event handlers, and javascript: URIs are stripped for security.

Ad Code (Starter+)

Insert ad network code (e.g., Google AdSense):

{
  "theme_config": {
    "adCode": "<ins class='adsbygoogle' data-ad-client='ca-pub-xxx'></ins>"
  }
}

The ad code is rendered between the post content and comments section.

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Default Theme

Postlark’s default theme includes:

• Fluid typography (responsive font sizes)
• Automatic dark mode (prefers-color-scheme)
• Code block syntax highlighting with copy button
• Reading progress bar
• Skip-to-content link (accessibility)
• Responsive images