For height and width you have two options. Setting it in your HTML or using the API to crop your images on the fly. For perfect images, we recommend a combination of both.
The API will auto crop your image to the height/width of the outermost HTML element. For example, the following will generate a screenshot that is 400px wide and 400px tall.
<div style="height: '400px'; width: '400px'"><h1>Hello, world</h1></div>
Margins are respected by the API. To add padding around your image, you can do the following.
<div style="height: '400px'; width: '400px'; margin: 10px; border: 5px solid #03B875;"><h1>Hello, world</h1></div>
Once an image is generated, use our API to adjust the image to any size you need with the width and height params. When only one param is passed, the API will maintain the aspect ratio of the original image.
This is useful for displaying images at different resolutions without having to setup your own CDN.