Platforms Demonstrating Problem

Netscape Navigator 4 (all platforms)
Internet Explorer 4 (all versions)

Description of Problem

There are various absolute and relative length units that can be used in CSS documents. However, these units are not allways properly understood by the browsers. In particular, the following two problems are endemic:

• Ex length units (e.g., 1.4ex) are not properly evaluated relative to the current font size. Use other relative units instead (i.e., em units, or percentages)
• Percentage lengths, when evaluated for quantities such as element widths, margins, paddings or heights, are measured incorrectly. Both Netscape Navigator and Internet Explorer 4 calculate these values as a percentage of the width of the browser window , which is incorrect according to CSS (In CSS, the widths should be calculated relative to the width of the parent element.

These issues are demonstrated in two test documents, ex-lengths-a.html which demonstrates font sizes and text indents) and ex-lengths-b.html, which demonstrates percentage margins.

Possible Workarounds

You should avoid using "ex" units, and need to take into acccount the errors in how the browser's calculate percentage element widths. If possible, then, you can avoid using percentage widths.