HTML/CSS layout number to the power of expression (a^x)

HTML is rather limited when it comes to mathematical expressions. In principle, HTML specifications suggest that you use sup element for superscripts, so the sample expression would be

(<i>a</i> + <i>b</i> + √<i>c</i>)<sup>2<i>x</i> + <i>b</i></sup>

However, the implementations of sup in browsers are inconsistent and generally poor (causing e.g. uneven line spacing), so it is pragmatically better to use the span element with a class instead:

(<i>a</i> + <i>b</i> + √<i>c</i>)<span class=sup>2<i>x</i> + <i>b</i></span>

with CSS code like

.sup {
  position: relative;
  bottom: 1ex; 
  font-size: 80%;
}

Some reasons are explained on my page Math in HTML (and CSS). Also consider JavaScript-based libraries for pages containing complicated math expressions:

• KaTeX
• MathJax
• jqMath

The sample expression is a borderline case; it would look mathematically more correct if the square root were represented using a square root symbol with vinculum and not just √c, and trying to construct a vinculum using HTML and CSS gets rather dirty, but otherwise it can be reasonably handled with HTML and CSS.

HTML defines a <sup> tag for superscript. For example:

a<sup>x</sup>

of which you can alter the margins and vertical alignment with CSS.

You can use a <sup> element to display the exponent as a superscript of the base. The HTML involved would be:

(a+b+sqrt(c))<sup>(2x+b)</sup>

A better approach would be to use CSS to achieve the same result, for which you can use a span with the property:

vertical-align:super;

A demonstration can be seen here.