> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vortexpdf.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Prefer CSS page size
> Control whether CSS @page size rules take precedence over the specified paper size
The `prefer_css_page_size` parameter allows you to control whether CSS-defined page sizes take precedence over the API-specified paper size.
## Overview
When rendering a webpage to PDF, there can be a conflict between the page size specified in the API request (via the `size` parameter) and any page size defined in the document's CSS using `@page` rules. The `prefer_css_page_size` parameter determines which of these takes precedence.
## Parameter details
Controls whether CSS-defined page sizes take precedence over the API-specified paper size
## Usage
```javascript theme={null}
{
"parts": "https://example.com",
"size": {
"preset": "a4"
},
"prefer_css_page_size": true
}
```
## Behavior
* **`true`**: CSS page size defined in `@page` rules takes precedence over the `size` parameter. Content will be rendered using the dimensions specified in CSS.
* **`false`**: The `size` parameter takes precedence over any CSS-defined page size. Content will be scaled to fit the specified paper size.
## Use cases
This parameter is particularly useful for:
1. **CSS-driven layouts**: When your HTML content includes specific `@page` size rules that are essential to the layout design.
2. **Consistent sizing across sources**: When you want to ensure all documents use the same paper size regardless of their CSS settings.
3. **Web-to-print workflows**: When converting web content that already has print-specific CSS rules that should be respected.
## Example with CSS @page rules
Consider HTML content with the following CSS:
```css theme={null}
@page {
size: 5in 8in; /* Sets page size to 5 inches by 8 inches */
}
.content {
margin: 0.5in;
}
```
### With prefer\_css\_page\_size `true`
```javascript theme={null}
{
"parts": "Content",
"size": {
"preset": "a4"
},
"prefer_css_page_size": true
}
```
Result: The PDF will use the 5in × 8in size from the CSS, ignoring the A4 size specified in the API request.
### With prefer\_css\_page\_size `false`
```javascript theme={null}
{
"parts": "Content",
"size": {
"preset": "a4"
},
"prefer_css_page_size": false
}
```
Result: The PDF will use the A4 size (210mm × 297mm) specified in the API request, and the content will be scaled to fit.