Defines a measurement relative to the height of a font in em spaces. Because an em unit is equivalent to the size of a given font, if you assign a font to 12pt, each em unit would be 12pt, thus 2em would be 24pt.

In this case, we should see the browser continue to parse the value of color as “red textdecoration: underline” before it sees a closing semicolon. The font-style property that follows would then be used. Because the color property has an illegal value, it should be ignored.

The first CSS specification to become an official W3C Recommendation is CSS level 1, published on December 17, 1996. Håkon Wium Lie and Bert Bos are credited as the original developers.

CSS level 2 revision 1, often referred to as “CSS 2.1”, fixes errors in CSS 2, removes poorly supported or not fully interoperable features and adds already implemented browser extensions to the specification. To comply with the W3C Process for standardizing technical specifications, CSS 2.1 went back and forth between Working Draft status and Candidate Recommendation status for many years. CSS 2.1 first became a Candidate Recommendation on February 25, 2004, but it was reverted to a Working Draft on June 13, 2005 for further review.

Here is no single, integrated CSS4 specification,[42] because it is split into separate modules. However, there are “level 4” modules.

Values for margin such as auto generally are used when centering blocks with textalign for content.

In the case of some elements such as <img>, the CSS float property is more appropriate than text-align.