css-generate 0.9943
Low-vision stylesheet generator
License: Apache 2
Requires Python: >=2.0

# css-generate
Low-vision stylesheet generator from https://ssb22.user.srcf.net/css/
(also [mirrored on GitLab Pages](https://ssb22.gitlab.io/css/) just in case)

Many modern Web browsers allow users to set their own CSS
stylesheets for accessibility purposes. It can be difficult to write a comprehensive
accessibility stylesheet by hand, especially if you
want to work around browser bugs and the
difficulties posed by complex websites. So I made this program to
generate long CSS files with workarounds for many problems.

You can adjust the Python code to your needs:
it works in both Python 2 and Python 3, and is
also available as a PyPI module so you can use
`pip install css-generate` or `pipx run css-generate`.
Alternatively, you can try one of the presets on the
[web page](https://ssb22.user.srcf.net/css/)
(which, if you have Javascript, has an interactive chooser: the code
for this is also generated by the script).

Size "unchanged" lacks size-related layout changes; this can be useful
if you do not need large print, or your monitor is big enough for the
browser's built-in zoom controls to be enough, but you still need to
change the colours (see
[advantages of dark backgrounds](https://ssb22.user.srcf.net/css/dark.html)).

What is the best pixel size?
----------------------------

You could just experiment, but if you frequently change between
different setups and/or have variable sight then it might help to know
how to choose a size without constantly re-experimenting:

1. You need to know the best size in points (36, 48 or whatever) for
   text you read **at the distance of the screen**.

    - First you need to know your normal distance to the screen. You
      can move the screen nearer, but the limits will vary with the
      type of mounting and the size of your keyboard, desk, chair,
      etc; you need to be aware of this variation if you use different
      computers. Also, if you have variable sight, remember to allow
      yourself room to get even nearer when your sight is worse (and
      without hurting your posture too much), which is usually easier
      than temporary size changes.

    - Divide the screen's distance by your normal reading distance for
      printed text (both measured from your eyes to the text itself,
      ignoring any magnifying device in between), and multiply by the
      size in points of the printed text you prefer to read.

    - If you normally use a magnifier for printed text but cannot use
      it for the screen, multiply your answer by the scale factor of
      this magnifier.

    - If you have a full-screen magnifier (fresnel lens) permanently
      mounted to the screen, then **divide** your answer by the scale
      factor of this magnifier.

    - Do **not** try to work out your size by setting the "point
      size" on the screen of a wordprocessor or similar, because that
      might not be calibrated correctly.

2. Let `P` be your on-screen point size, `H` and `V` be the horizontal and
   vertical resolution of your monitor, and `D` be its size in inches
   (measure across the diagonal if you don't know, and if you're on an
   old CRT monitor then you should subtract about an inch from the
   rated figure whereas TFT monitors' figures are OK as they are).
   Your pixel size is the square root of `(H*H + V*V)`, divided by `D`,
   multiplied by `P` and divided by 72.  (If your monitor has the old
   standard 4x3 aspect ratio then this simplifies to `P*V/D * 5/216`.)

3. With some browsers, you'll need to divide this by the browser's
   value of `window.devicePixelRatio`

How to install a stylesheet
---------------------------

Save the stylesheet to a file on your disk, and do what is appropriate
for your browser:

**Firefox:** On the desktop version, locate your profile directory
[as described on mozilla.org](http://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data#w_how-do-i-find-my-profile),
and save the file as `userContent.css` in the `chrome` subdirectory of
your profile directory (if no `chrome` subdirectory exists, create it).

  * On Firefox 69+, you also have to go to `about:config` and turn on
    `toolkit.legacyUserProfileCustomizations.stylesheets`
  
  * You have to restart Firefox when changing userContent.css; on
    GNU/Linux you might want the provided [togglecss
    script](https://ssb22.user.srcf.net/css/togglecss.sh) to toggle the presence of userContent.css
    and restart Firefox.
  
  * On Firefox 51, you'll also need to go into about:config, set
    browser.tabs.remote.autostart.2 to false and restart. This was
    fixed in Firefox 52 (bug 1333157).
  
  * Not always possible on mobile Firefox: for example in Android
    you'll need to "root" your device before you can see the profile
    directory (and that's not always feasible). You might try the
    "Stylish" plugin, but it doesn't always work as well as installing
    a local stylesheet (colours are occasionally overridden by the
    site; black-on-white might work better).
  
  * Some versions of Firefox scale their pixels at high DPI settings,
    so the stylesheet size needs to be reduced to
    compensate. (E.g. Firefox 3+ on Windows, and more recent versions
    of Firefox on GNOME 3 with text-scaling-factor set.)
  
  * If you use dark backgrounds, some versions of Firefox on Windows
    display a white background around the page (so any overspill text
    that is not dark will become unreadable) unless you go into high
    contrast mode. However if you then come out of high contrast mode,
    the fix will persist. (High contrast mode is a nice idea but it
    does break a lot of applications.)

  * If you are using these stylesheets merely to get a dark background
    at size "unchanged" then you might also want set Firefox's
    "Settings / General / Language and Appearance / Web site
    appearance" to "Dark" and remove lines containing
    Ffx&shy;Dark&shy;Mode&shy;Exceptions CSS to allow websites known
    to have their own automatic "dark modes" to work, but this can
    result in a brief white flash while the site is loading.

**Internet Explorer:** Go to Tools / Internet Options / Accessibility
and set that file as a user-supplied stylesheet.

  * If you are using a low resolution or a high DPI setting as a means
    of getting Windows to magnify consistently, and if as a result of
    this the dialogue boxes won't entirely fit on your screen, you
    _may_ be able to reach Accessibility by clicking on General in
    Tools/Internet Options, pressing Tab 13 times (in IE6) or 12 times
    (in IE7), and pressing Enter.  But this is likely to change in
    different versions of IE.
  
  * If you also set text and background colours, _do not_ check
    "always use these colours" because it will override the
    stylesheet.

  * Some versions of **Windows XP** will override this stylesheet when
    in high contrast mode, and the result is not always readable. You
    may have to come out of high contrast mode when browsing.

**Safari:** Go to Safari / Preferences / Advanced / Style sheet,
select Other, and select the file

**Google Chrome:** Create a directory with the
stylesheet saved as `userContent.css` and a file called
`manifest.json` with the following content:

    {"manifest_<wbr>version": 3,
    "name": "Low-vision stylesheet",
    "version": "1",
    "content_scripts": [{
       "matches": ["<all_urls>"],
       "css": ["userContent.css"]}]}

then go to `chrome://extensions` and with Developer Mode
turned on "load unpacked extension" and point to this directory.

  * On recent Chrome versions you can also try
    `chrome://flags/#enable-force-dark` instead of using
    this CSS for dark mode
    
    * Or you could try running Chrome with
      [Web Adjuster](https://ssb22.user.srcf.net/adjuster/)
    
      * e.g. on GNU/Linux set up a `/usr/local/bin/x-www-browser`
        script to do `python` (full path to adjuster.py)
        `--browser="google-chrome --proxy-server=localhost:28080 $*"`
        `--real_proxy --delete_doctype --address=localhost`
        `--headAppendCSS=http://` (URL of stylesheet goes here),
        although SSL sites will need domain-rewriting
      
      * A white background will still show in Chrome's blank page and
        new tab screen etc (so you might want to set a homepage); when
        navigating _within_ sites it should happen rarely if ever. (If
        reloading already-visited pages, clear the cache.)
        At any rate, Chrome is likely to cope less well
        than other browsers with some sites' use of CSS
        priorities, because the CSS we insert does not
        have the extra privileges given it by other browsers.

**Midori:** Before version 0.0.20, use Edit / Preferences / Behaviour /
User Stylesheet. In later versions, go to Tools / Extensions (or
Preferences / Extensions), enable ‘User Addons’, and save the .css
file in `.local/share/midori/styles/`.
Some versions of Midori do not have this functionality.

**KDE browsers:** In Rekonq, use Configure / Appearance / Stylesheets.
In the older Konqueror browser, go to "Settings", "Configure
Konqueror", "Stylesheets" (in some versions it's a tab of
"Appearance"), "user-defined stylesheet" and set the filename; you may
have to restart Konqueror. Some Konqueror versions have a bug that
causes it to completely fail to apply the stylesheet; if you have an
affected version then you might need to switch to another browser.

**Opera 12 or below:** (these instructions do _not_ apply to the new
Opera 15 which is basically Chromium see above)
Opera menu / Settings / Preferences / Advanced / Content / Style options / My style sheet

  * Some versions (e.g. 12) will not style "textarea" edit controls
    unless you apply the stylesheet from a bookmarklet. Even then the
    borders may be missing.
  
  * Opera 12 **can crash** on some sites. You might be able to make it
    more stable by disabling the `:first-letter`, `:first-line` and
    `:hover` rules (e.g. replace `:first` with `:girst` and `:hover`
    with `:gover` throughout), but this is not a complete solution.
  
  * You might also want to set a background colour in the "Web pages"
    tab: this will be shown when new tabs etc are taking a while to
    load

**Otter:** Go to Tools / Preferences / Advanced / Content / User style sheet
and type in the full path or Browse to it.
Not yet working if you're using the newer QtWebEngine instead of QtWebKit.

**OLPC browser:**
Save the file as `~/.sugar/default/gecko/user-stylesheet.css` and
restart. (When calculating the best stylesheet size, remember the
OLPC's screen is 1200x900 and 7.5 inches.)

For other setups (including some mobiles) you can try
[Web Adjuster](https://ssb22.user.srcf.net/adjuster/);
for demonstration purposes there is an installation of Web Adjuster
with these stylesheets at `large-print-websites.appspot.com`

All material (c) Silas S. Brown unless otherwise stated.
Android is a trademark of Google LLC.
Firefox is a registered trademark of The Mozilla Foundation.
Google is a trademark of Google LLC.
Javascript is a trademark of Oracle Corporation in the US.
Linux is the registered trademark of Linus Torvalds in the U.S. and other countries.
Python is a trademark of the Python Software Foundation.
Safari is a registered trademark of Apple Inc.
Windows is a registered trademark of Microsoft Corp.
Any other trademarks I mentioned without realising are trademarks of their respective holders.