Why does “<! --” comment out a style rule, but “<!--” does not?

Question

Take it easy on me. I am just learning HTML.

Accroding to http://www.w3.org/TR/html-markup/syntax.html#comments and many other sites I\'ve seen such as this http://www.w

Answer 1

The string does not comment out anything. Instead, in CSS it is a syntax error, and the CSS error processing rules imply in this case that all of the style sheet is ignored.

The string ) is permitted and ignored (skipped) in certain contexts. Thus, the style sheet

is taken as

{border: 1px solid gray;}

You can check this out using the W3C CSS Validator. In the first case, with the space, an error is reported, and no valid CSS rules are reported. In the second case, no error is reported, and the rule is shown as valid.

In CSS, a comment always starts with /* and ends with */.

The reason for the special rules for is that very long ago (and we are talking about the time when Netscape 1 was still in use), some browsers did not recognize the style element at all. This implied that they ignored the tags and processed the content between them as if it were normal HTML content. This would have caused the style sheet to be displayed inside the page on such browsers. To prevent this, to “hide the style sheet”, the style sheet was wrapped between the HTML comment delimiters. Old browsers then simply ignored the content of the style element. But then a special rule had to be added to CSS spec to allow the delimiters.

This is ancient history, but old habits prevail and are even copied from other people’s code without understanding what they mean. There has been no reason to “hide the style sheet” for a long, long time, and the trick has now become a potential risk (due to possible interference with XHTML rules or to people’s confusion and typing errors).

So, never use

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