Not an expert on webshit stuff, does it mean that the font will now be sent to all visitors even if they already have it installed?
The above CSS does that, yes.
However, with
@font-face { font-family: 'DejaVu Sans Mono Webfont'; src: url('uri/DejaVuSansMono.woff2') format('woff2'), url('uri/DejaVuSansMono.woff') format('woff'); /* This is a free font; see license at uri/DejaVuSansMono.txt */ }and in the CSS snippets for tt and code elements,
font-family: 'DejaVu Sans Mono', 'DejaVu Sans Mono Webfont', 'monaco', 'lucida console', 'courier new', monospace;then OS-installed DejaVu Sans Mono would be preferred, otherwise the webfont would be used; and browsers that don't want to use the webfont fall back to the same list as now.
Also, I'm pretty sure at least some of the extensions I have installed at least on some systems mentioned blocking font downloads on the basis of security.
That only happens when the webfont is hosted elsewhere, not in the same domain as the page was loaded from.
As far as I'm concerned any mono font with equal character width is a good enough mono font ![Confused :-//](https://www.eevblog.com/forum/Smileys/default/confused0024.gif)
The problem is, their Unicode glyph coverage varies a lot, so they display rectangles instead of the desired glyph. Anything outside Latin letters may, or may not be displayed correctly.
I'd leave it alone as the browser likely has better fonts locally and users may have set things up to improve accessability of websites which then get overruled
Impossible, for DejaVu Sans Mono. The webfont created using the instructions I listed is the same as the TrueType original,
DejaVu Sans Mono.ttf. The Web Open Font format simply compresses it (lossless compression) and adds an XML description to it. In particular, hinting information is retained.
If you consider the alternative fonts, like Monaco, their Unicode coverage is worse than DejaVu Sans Mono, so using those already installed "better fonts" some glyphs us that do have DejaVu Sans Mono installed (or use the equivalent webfont), may see just rectangles instead of the proper intended glyphs.