For users arriving via Tech News:
You can override the font size to your liking using a snippet like this, added to your user style subpage – for example, global.css:
.mw-editfont-monospace, .mw-editfont-sans-serif, .mw-editfont-serif { font-size: 13px !important; }
See the table below to find out what font size your browser was using before.
Note that fractional values may not work well with wikitext syntax highlighting.
Task summary
For historical reasons we've allowed inconsistent browser-default styles to apply to textarea#wpTextbox1 (and until recently we allowed the browser to set the font family: T170223)
This leads to inconsistency across browsers, which can lead to a jarring UX when changing browser, and also problems implementing new edit areas with a consistent feel (e.g. Flow, VE source mode), or extensions that require font-size matching (e.g. CodeMirror syntax highlighting, see T180678)
The issue is further complicated by the fact we use font-family:monospace (instead of the "monospace, monospace" hack: T176636) which applies extra font size rules in some browsers (Firefox) and some versions.
The current font sizes we get are (all in px):
| Browser | OS | Monospace | Serif/Sans-serf | Notes |
|---|---|---|---|---|
| Chrome | Win/Ubuntu | 13.3333 | 13.3333 | (Likely more precision, but reporting tool rounds to 4dp) |
| IE/Edge | Win (All) | 13.33 | 13.33 | (as above) |
| Firefox | OSX/Win | 13 | 16 | |
| Firefox | Ubuntu | 12 | 16 | |
| Safari | OSX (All) | 11 | 11 | |
| Chrome | OSX | 11 | 11 | |
It would seem sensible to standardise on 13.3333 to affect the fewest number of users. Chrome+IE/Edge users (76%) will be unaffected except for OSX (~4%). Firefox users (15%) will get a barely noticeable change. The only users significantly affected will be OSX users (12%) who will notice a significant increase (from the currently very small, and arguably not-very-accessible 11px).
Edit: Also FF users who have changed their edit font to serif/sans-serif will get a significant change, but very few people use that preference at all (https://phabricator.wikimedia.org/T170223#3539911)
Edit2: We are going with 13px. It should be basically indistinguishable from 13.3333px, and avoids rounding errors further down the chain.
Screenshots
Monospaced
| Browser/OS | Before | After |
|---|---|---|
| Windows/Firefox |  |  |
| Windows/Chrome |  |  |
| Windows/Edge |  |  |
| Ubuntu/Firefox |  |  |
| Ubuntu/Chrome |  |  |
| OSX/Firefox |  |  |
| OSX/Chrome |  |  |
| OSX/Safari |  |  |
Sans-serif
| Browser/OS | Before | After |
|---|---|---|
| Windows/Firefox |  |  |
| Windows/Chrome |  |  |
| Windows/Edge |  |  |
| Ubuntu/Firefox |  |  |
| Ubuntu/Chrome |  |  |
| OSX/Firefox | ||
| OSX/Chrome | ||
| OSX/Safari | ||
