HTML Guide for expected digit

Bad value “%” for attribute “width” or “height” on element “object”: Expected a digit but saw “%” instead.

Attribute values for width and height on the object element must be a valid integer (pixels), not a percentage.

In HTML5, the width and height attributes for the <object> element must be specified in pixels as an integer value, such as height="500". Using percentage values like height="100%" is not allowed in the attribute according to the HTML living standard and will trigger a validation error. To set a percentage height, use the CSS width and height properties instead.

Correct usage (pixels via attribute):

<object data="example.pdf" type="application/pdf" width="600" height="400"></object>

Correct usage (percentage via CSS):

<object data="example.pdf" type="application/pdf" style="width: 100%; height: 100%;"></object>

Example of a full valid HTML document using CSS for 100% height:

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Object Height Example</title>
  <style>
    html, body {
      height: 100%;
      margin: 0;
    }
    object {
      height: 100%;
      width: 100%;
      display: block;
    }
  </style>
</head>
<body>
  <object data="example.pdf" type="application/pdf"></object>
</body>
</html>