W3-startup faulure

[Cor Gest]

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In GNU Emacs 21.3.2 (i486-slackware-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2003-05-23 on midas
configured using `configure  i486-slackware-linux --prefix=/usr --with-x11 
--with-x-toolkit --with-pop'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: C
  locale-coding-system: nil
  default-enable-multibyte-characters: t

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

after downloading W3-source and standard install as mentioned by `INSTALL'
First execution give error:

Backtrace of the error

Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
  +(nil 12)
  font-spatial-to-canonical("+12pt")
  css-expand-length("+12pt" t)
  css-expand-value(height "+12pt")
  css-parse-args(238 257)
  css-parse("file:/usr/local/share/default.css" nil nil)
  w3-find-default-stylesheets()
  w3-refresh-stylesheets()
  w3-do-setup()
  w3()
* call-interactively(w3)
  execute-extended-command(nil)
  call-interactively(execute-extended-command)
  recursive-edit()
  byte-code("Æ!ˆÇ ˆÈ      !ˆ\nƒ?
  debug(error (wrong-type-argument number-or-marker-p nil))
  +(nil 12)
  font-spatial-to-canonical("+12pt")
  css-expand-length("+12pt" t)
  css-expand-value(height "+12pt")
  css-parse-args(238 257)
  css-parse("file:/home/cor/.w3/default.css" nil nil)
  w3-find-default-stylesheets()
  w3-refresh-stylesheets()
  w3-do-setup()
  w3()
* call-interactively(w3)
  execute-extended-command(nil)
  call-interactively(execute-extended-command)