HTML Guide for CSS

Invalid values have been assigned to the white-space CSS property.

The white-space property in CSS controls how whitespace and line breaks inside an element are handled. Only specific values are valid for this property. According to the CSS specification, valid values for white-space include:

/* Single keyword values */
white-space: normal;
white-space: pre;
white-space: pre-wrap;
white-space: pre-line;

/* white-space-collapse and text-wrap-mode shorthand values */
white-space: wrap;
white-space: collapse;
white-space: preserve nowrap;

/* Global values */
white-space: inherit;
white-space: initial;
white-space: revert;
white-space: revert-layer;
white-space: unset;

Using the width attribute with an invalid value or on an element where it’s not allowed causes a “types are incompatible” error.

The width attribute must only be used on certain elements, like img, canvas, input (of type image), or video. Its value should be a valid integer, representing the number of CSS pixels, without units. Using CSS units like px or % directly in the attribute, or placing the attribute on unsupported elements, will trigger this validation message.

Correct usage:

<img src="photo.jpg" width="400" alt="Sample photo">

Incorrect usage (with units):

<img src="photo.jpg" width="400px" alt="Sample photo">

Incorrect usage (on unsupported element):

<div width="400">Content</div>

To set width via CSS instead, use the style attribute or an external stylesheet:

<div style="width: 400px;">Content</div>

For styling, always use CSS when possible; reserve the width attribute for the few HTML elements that specifically support it, and ensure the value is a simple number without units.