In the tag <@> the value "~" must be quoted.

The tag <@> is an extension by Microsoft and not part of the HTML standard. 

The attribute "~" is not defined for the tag <@>.

It is impossible to set the frame dimensions as they are defined.

The tag <@> is only part of "HTML 4.0 Frameset".

The tag <@> is an extension by Netscape and not part of the HTML standard. 

The tag <@> should no longer be used since HTML 4.0.

The color name "°" is not part of the HTML standard.