Adding HTML entities using CSS content

You have to use the escaped unicode :

Like

.breadcrumbs a:before {
  content: '\0000a0';
}

More info on : http://www.evotech.net/blog/2007/04/named-html-entities-in-numeric-order/

CSS is not HTML.   is a named character reference in HTML; equivalent to the decimal numeric character reference  . 160 is the decimal code point of the NO-BREAK SPACE character in Unicode (or UCS-2; see the HTML 4.01 Specification). The hexadecimal representation of that code point is U+00A0 (160 = 10 × 16¹ + 0 × 16⁰). You will find that in the Unicode Code Charts and Character Database.

In CSS you need to use a Unicode escape sequence for such characters, which is based on the hexadecimal value of the code point of a character. So you need to write

.breadcrumbs a:before {
  content: '\a0';
}

This works as long as the escape sequence comes last in a string value. If characters follow, there are two ways to avoid misinterpretation:

a) (mentioned by others) Use exactly six hexadecimal digits for the escape sequence:

.breadcrumbs a:before {
  content: '\0000a0foo';
}

b) Add one white-space (e. g., space) character after the escape sequence:

.breadcrumbs a:before {
  content: '\a0 foo';
}

(Since f is a hexadecimal digit, \a0f would otherwise mean GURMUKHI LETTER EE here, or ਏ if you have a suitable font.)

The delimiting white-space will be ignored, and this will be displayed  foo, where the displayed space here would be a NO-BREAK SPACE character.

The white-space approach ('\a0 foo') has the following advantages over the six-digit approach ('\0000a0foo'):

• it is easier to type, because leading zeroes are not necessary, and digits do not need to be counted;
• it is easier to read, because there is white-space between escape sequence and following text, and digits do not need to be counted;
• it requires less space, because leading zeroes are not necessary;
• it is upwards-compatible, because Unicode supporting code points beyond U+10FFFF in the future would require a modification of the CSS Specification.

Thus, to display a space after an escaped character, use two spaces in the stylesheet –

.breadcrumbs a:before {
  content: '\a0  foo';
}

– or make it explicit:

.breadcrumbs a:before {
  content: '\a0\20 foo';
}

See CSS 2.1, section "4.1.3 Characters and case" for details.