The header

Look at the text - it should not be the font face red and it should not be larger than in the paragraphs below. If the color of this text is red and it is larger than other basic text, the browser reads the incorrect set @import at-rule.

With MS IE 6.0 for Windows the behavior is DTD-dependent. It and some other browsers have so-called DTD-switch. This document is HTML 4.01 Strict. The version, which doesn't have the DTD-declaration.

From the following texts it is possible to see browser accept invalid class and id names, when the names have been judged according to the CSS-specifications. It is however remarkable that specifications are different. I list below remarkable differences:

Browsers are not fair to compare with each others. Instead they should compare to the specification, which they are intended to support (the browser factory had informed, that the browser should work according to certain specification) or what kind of support they can be expected according to the age of the browser.

Browsers, which I and a Mac user have been tested accept names of id and class selectors at the following ways (if not otherwise informed all browsers are Windows browsers; st.-comp = standard-compliant):

MS IE 4.0 MS IE 5.0 MS IE 5.5,
MS IE 6.0
MS IE 6.0
MS IE 5.0 for Mac
Netscape 4.04 Netscape 4.79 Netscape 6.0 Mozilla 0.9+, Netscape 6.1+ Opera 5.12, Opera 5.0 Beta 4 for Mac Opera 6.0x Opera 7.0 Beta1
Expected support: CSS1 CSS2 CSS2 CSS2 CSS1 CSS2 CSS2 CSS3 CSS1 CSS2 CSS2.1

Here is class="1abc".

[NOT OK!] [NOT OK!] [NOT OK!]               [NOT OK!]

Here is class="-abc".


Here is class="a_bc".

  [OK!] [OK!] [OK!]   [OK!]   [OK!]   [OK!] [OK!]

Here is id="1abc"

[NOT OK!] [NOT OK!] [NOT OK!]       [NOT OK!] [OK!]      

Here is id="-abc".

[NOT OK!] [NOT OK!]         [NOT OK!] [OK!] (?) [NOT OK!] [NOT OK!] [NOT OK!]

Here is id="a_bc".

  [OK!] [OK!] [OK!]   [OK!]   [OK!]   [OK!] [OK!]


  1. The information that Opera 5.x doesn't support fixes, which are made to the CSS2 specification and new Netscape/ Mozilla works according to CSS3 base on some e-mail discussions. I can't give Web-addresses in order to check these matters.
  2. Grouping rules might change the situation with Opera.