2.2.8 [HTML] Section 9.3.4, Preformatted text: The PRE element
The specification states:
width = number [CN] Deprecated. This attribute provides a hint to visual user agents about the desired width of the formatted block. The user agent can use this information to select an appropriate font size or to indent the content appropriately.
All Document Modes (All Versions)
The width attribute of the PRE element is not supported.