IE6 Launch = Unpleasant Surprises

Beginning of the end of browser backwards compatibility.

Internet Explorer has always been tolerant of bad HTML — in deference to the fact that much of the inferior HTML was produced by Microsoft products. The launch of IE6 signals the end of this tolerance.

The default behavior of IE6 tends to a much stricter interpretation of W3C standards than most people —and most tools— are prepared for.

Examples:
• CSS rules require that units be specified and that there be no spaces between the number and unit.

  P {font-size: 14	}
  P {font-size: 14 px	}

  IE6, following the standard, will ignore both these rules. Earlier versions accepted both as 14px.
• Watch case-sensitivity in class and ID names. IE6 will not apply styles where the class name in the style sheet does not exactly match the class name in the HTML.
• Keywords, such as named colors ("red") cannot be quoted in style sheets.
• Hexadecimal color values must be preceded by the # sign.