Superscript in CSS only?

Question

How can I get superscript done, only in CSS?

I have a stylesheet where I mark the external links with a superscript character, but I'm having a hard time getting the character aligned correctly.

What I have currently, looks like this:

a.external:after {
  font-size: 50%;
  vertical-align: top;
  content: "+";
}

but it doesn't work.

Naturally, I'd use the <sup>-tag, only if content would allow for HTML...

Answer 1

Honestly I don't see the point in doing superscript/subscript in CSS only. There's no handy CSS attribute for it, just a bunch of homegrown implementations including:

.superscript { position: relative; top: -0.5em; font-size: 80%; }

or using vertical-align or I'm sure other ways. Thing is, it starts to get complicated:

• CSS superscript spacing on line height;
• Beware CSS for Superscript/Subcript on why you arguably shouldn't style superscript/subscript with CSS at all;

The second point is worth emphasizing. Typically superscript/subscript is not actually a styling issue but is indicative of meaning.

Side note: It's worth mentioning this list of entities for common mathematical superscript and subscript expressions even though this question doesn't relate to that.

The sub/sup tags are in HTML and XHTML. I would just use those.

As for the rest of your CSS, the :after pseudo-element and content attributes are not widely supported. If you really don't want to put this manually in the HTML I think a Javascript-based solution is your next best bet. With jQuery this is as simple as:

$(function() {
  $("a.external").append("<sup>+</sup>");
};

Answer 2

Check out: http://www.cssdesignpatterns.com/Chapter%2012%20-%20ALIGNING%20CONTENT/Vertical-aligned%20Content/example.html

if looks like you want "vertical-align:text-top"

Answer 3

Have you tried vertical-align: super; ?

http://www.w3schools.com/Css/pr_pos_vertical-align.asp

Answer 4

http://htmldog.com/articles/superscript/

Works well in practice, as far as I can tell.

Answer 5

The CSS documentation contains industry-standard CSS equivalent for all HTML constructs. That is: most web browsers these days do not explicitly handle SUB, SUP, B, I and so on - they (kinda sorta) are converted into SPAN elements with appropriate CSS properties, and the rendering engine only deals with that.

The page is Appendix D. Default style sheet for HTML 4

The bits you want are:

small, sub, sup { font-size: .83em }
sub             { vertical-align: sub }
sup             { vertical-align: super }

Answer 6

I was working on a page with the aim of having clearly legible text, with superscript elements NOT changing the line's top and bottom margins - with the following observations:

If for your main text you have line-height: 1.5em for example, you should reduce the line-height of your superscript text for it to appear correctly. I used line-height: 0.5em.

Also, vertical-align: super works well in most browsers but in IE8 when you have a superscript element present, the rest of that line is pushed down. So instead I used vertical-align: baseline together with a negative top and position: relative to achieve the same effect, which seems to work better across browsers.

So, to add to the "homegrown implementations":

.superscript {
    font-size: .83em;
    line-height: 0.5em;
    vertical-align: baseline;
    position: relative;
    top: -0.4em;
}

Answer 7

This is another clean solution:

sub, sup {vertical-align: baseline; position: relative; font-size: 70%;} /* 70% size of its parent element font-size which is good. */
sub {bottom: -0.6em;} /* use em becasue they adapt to parent font-size */
sup {top: -0.6em;} /* use em becasue they adapt to parent font-size */

In this way you can still use sup/sub tags but you fixed their idious behavior to always screw up paragraph line height.

So now you can do:

  <p>This is a line of text.</p>
  <p>This is a line of text, <sub>with sub text.</sub></p>
  <p>This is a line of text, <sup>with sup text.</sup></p>
  <p>This is a line of text.</p>

And your paragraph line height should not get screwed up.

Tested on IE7, IE8, FF3.6, SAFARI4, CHROME5, OPERA9

I tested using a p {line-height: 1.3;} (that is a good line height unless you want your lines to stick too close) and it still works, cause "-0.6em" is such a small amount that also with that line height the sub/sub text will fit and don't go over each other.

Forgot a detail that might be relevant I always use DOCTYPE in the 1st line of my page (specifically I use the HTML 4.01 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"&gt;). So I don't know if this solution works well when browser is in quirkmode (or not standard mode) due to lack of DOCTYPE or to a DOCTYPE that does not triggers Standard/Almost Standard mode.