Stefan Ram wrote:
>    When a non-italic symbol follows an italic symbol, the
>    distance betweeen them somtimes is too small. For example:
> 
> <i>ƒ</i>)
> 
>    . The italicized ƒ may "touch" the parenthesis in some
>    browsers.
This also happens (quite often) with the simpler and more common case
<i>f</i>)
and even more often with
<i>f</i>(
(I'm biting my fingers to not comment the use of LATIN SMALL LETTER F 
WITH HOOK U+0192 ƒ except by stating that the character is rarely used 
and has no standardized use, and since it is essentially a calligraphic 
(or script) “f” taken to different uses, it is very slanted in many 
fonts, and if you italicize it, you probably get very, very slanted 
italics or faux italics.)
>    To avoid this, one could introduce a small space:
> 
> <i>ƒ</i> )
Yes, but   is U+200A HAIR SPACE, which is very thin, intended to 
correspond to the thinnest space available in traditional typography. It 
may well be insufficient here. Generally, you would need to select among 
the fixed-width spaces in Unicode, depending on the content.
Moreover, fixed-width spaces are spaces and have line breaking property 
value of BA (break opportunity after), so a program may decide to break 
the line after it. (Whether this happens depends on adjacent characters 
and other factors.) Using format control characters or CSS you might 
prevent that, but this make approach more complicated.
There is a limited repertoire of fixed-width characters, and their 
widths aren’t really fixed but depend on font. For more flexible and 
more predictable tuning, you could use CSS, e.g.
<i class=pad>f</i>)
with
.pad { padding-right: 0.15em; }
>    It would be very cumbersome to manually (or even
>    programmatically) adjust all those character distances.
It is. But you could handle just the most disturbing cases with CSS, 
using a pre-made set of class definitions for various sizes of padding.
>    Therefore, the best thing would be for the browser to
>    do this. The browser has all the information needed.
>    But it does not seem to care.
Browsers, or programs in general, don’t do such things. For some years, 
browsers have supported kerning (either by default or upon request with 
the CSS property font-kerning) for character pairs. For example, if an 
HTML document has the letter pair VA and it is rendered using an 
OpenType font that has a kerning table entry for it, the odds are 
probably that it will be shown as kerned closer to each other. But this 
is not based on analysis of the glyphs for the character and the 
author’s or viewer’s opinion on how close the characters should be but a 
font designers idea of that and specific information (entered into the 
kerning table of the font) how certain character pairs should be rendered.
So browsers don’t “think” about such things even for glyphs taken from 
the same font and rendered with in the same font style. It would much 
more to ask to do something with, say, an italic “f” followed by a 
non-italic “)”.
Yucca, 
https://jkorpela.fi