For HTML, use the HTML-entity:
In additional you may add the Unicode directive to make sure it always render as text
&#579;&#65038; (need to be close together).
The easiest way of including the BitCoin-character is by simply copying the raw Unicode character:
and with the Unicode text-mode directive:
(carefully remove the
< characters without deleting the invisible character after the bitcoin sign..)
You can test it by pasting it into notepad++/notepad2 and strip-away the visible characters, to make sure you’ve also got the hidden character :)
Here is a small HTML that is flexible in font-size,
it is same code in different width/height sizes (you can right click it to show the IFRAME’s source),
it is includes a blocking of the the text-selection so you could include it inline, to allow users to copy a numeric value, without the BitCoin character itself.