/* ==========================================================================
osler-theme — self-hosted webfonts
--------------------------------------------------------------------------
Goes at osler/static/theme/fonts.css, loaded from base.html BEFORE
tokens.css so the faces exist by the time the token stacks name them:
---- no third-party font host, deliberately --------------------------
Every face is served from this application's own static path. Not a
preference — three reasons, in order of how much they matter here:
1. The projector runs in seminar rooms and lecture theatres on hospital
wifi. A font that arrives late is a slide that reflows in front of a
room; a font that does not arrive is a fallback nobody chose. The
artefact ladders and the one-screen presenter constraint were tuned
against known metrics.
2. A font request to a third party is a request that carries a referrer
and an IP from a clinical teaching session to a company that is not
us. There is no consent story for that and no need for one.
3. It removes a runtime dependency from a tool whose whole governance
posture is about knowing where things came from.
---- licences ----------------------------------------------------------
All three are SIL Open Font License 1.1, which permits bundling and
redistribution with the application:
IBM Plex Sans, IBM Plex Mono
Copyright © 2017 IBM Corp., Reserved Font Name "Plex". OFL 1.1.
Source: github.com/IBM/plex releases.
Libre Caslon Text
Copyright © 2012 Pablo Impallari, Rodrigo Fuenzalida,
Reserved Font Name "Libre Caslon". OFL 1.1.
Source: github.com/impallari/Libre-Caslon-Text.
OFL 1.1 requires the licence text to travel with the fonts. Ship
theme/fonts/OFL-Plex.txt and theme/fonts/OFL-LibreCaslon.txt alongside
the woff2 files; that is the whole obligation.
---- the slashed zero, and why it is a CSS feature and not a build ----
IBM Plex ships a slashed zero as an OpenType feature, reachable as either
`zero` or `ss03`. It is NOT the default glyph, which is why --mono-features
exists and why components.css has to apply it — the token alone does
nothing.
The alternative is baking it in with a feature-freezing tool so it needs no
CSS. Do not: that produces a Modified Version, and OFL 1.1's Reserved Font
Name clause then forbids shipping it as "IBM Plex Mono". A renamed fork of
a clinical tool's join-code font is a maintenance liability for no gain.
VERIFY ON THE ACTUAL FILE before trusting the join code, because a
subsetted or re-generated woff2 can lose GSUB features:
from fontTools.ttLib import TTFont
f = TTFont("IBMPlexMono-Regular.woff2")
print(sorted({r.FeatureTag for r in f["GSUB"].table.FeatureList.FeatureRecord}))
`zero` must appear in that list. If it does not, the slashed zero is not
available and the decision behind --mono-features has to be revisited —
the fallbacks are `ss03` on the same file, or accepting Plex's plain zero
and keeping a disambiguated face for join codes only. Say which, rather
than shipping a feature flag that silently does nothing.
---- weights ----------------------------------------------------------
400 / 500 / 600 only. --weight-medium is 500 and --weight-bold is 600;
nothing asks for 700 in the sans, and every weight shipped is a file the
room downloads. Libre Caslon Text has no 500 — it ships 400, 400 italic
and 700 — so the display face uses 400 for headings and 700 where a
genuine bold is called for.
========================================================================== */
/* ---- display: Libre Caslon Text ---------------------------------------- */
/* local() first throughout: if the machine already has the face, the room
downloads nothing. */
@font-face {
font-family: "Libre Caslon Text";
font-style: normal;
font-weight: 400;
font-display: swap;
src: local("Libre Caslon Text"),
url("fonts/LibreCaslonText-Regular.woff2") format("woff2");
}
@font-face {
font-family: "Libre Caslon Text";
font-style: italic;
font-weight: 400;
font-display: swap;
/* The login quotation is the only italic in the product. It is one file and
it is the sentence the whole page is built around. */
src: local("Libre Caslon Text Italic"),
url("fonts/LibreCaslonText-Italic.woff2") format("woff2");
}
@font-face {
font-family: "Libre Caslon Text";
font-style: normal;
font-weight: 700;
font-display: swap;
src: local("Libre Caslon Text Bold"),
url("fonts/LibreCaslonText-Bold.woff2") format("woff2");
}
/* ---- UI: IBM Plex Sans -------------------------------------------------- */
@font-face {
font-family: "IBM Plex Sans";
font-style: normal;
font-weight: 400;
font-display: swap;
src: local("IBM Plex Sans"),
url("fonts/IBMPlexSans-Regular.woff2") format("woff2");
}
@font-face {
font-family: "IBM Plex Sans";
font-style: normal;
font-weight: 500;
font-display: swap;
src: local("IBM Plex Sans Medium"),
url("fonts/IBMPlexSans-Medium.woff2") format("woff2");
}
@font-face {
font-family: "IBM Plex Sans";
font-style: normal;
font-weight: 600;
font-display: swap;
src: local("IBM Plex Sans SemiBold"),
url("fonts/IBMPlexSans-SemiBold.woff2") format("woff2");
}
/* ---- machine output: IBM Plex Mono -------------------------------------- */
/* Join codes, timers, counts, measurements. The face whose `zero` feature the
check above verifies. */
@font-face {
font-family: "IBM Plex Mono";
font-style: normal;
font-weight: 400;
font-display: swap;
src: local("IBM Plex Mono"),
url("fonts/IBMPlexMono-Regular.woff2") format("woff2");
}
@font-face {
font-family: "IBM Plex Mono";
font-style: normal;
font-weight: 500;
font-display: swap;
src: local("IBM Plex Mono Medium"),
url("fonts/IBMPlexMono-Medium.woff2") format("woff2");
}
@font-face {
font-family: "IBM Plex Mono";
font-style: normal;
font-weight: 600;
font-display: swap;
src: local("IBM Plex Mono SemiBold"),
url("fonts/IBMPlexMono-SemiBold.woff2") format("woff2");
}
/* ---- what is NOT declared here ------------------------------------------
--font-machine. The artefacts' lettering stays on the platform monospace
stack (ui-monospace / SF Mono / Menlo / Consolas) and the export flavours
name "DejaVu Sans Mono" explicitly. Shipping a webfont for the ECG headers
and the analyser printout would make the restyle reach into the frozen
objects through the back door — and it would mean a slide's artefact could
render in a different face from the same artefact exported to PNG.
Nine files, ~9 preloads' worth of bytes if all miss local(). Preload only
the two the first paint actually needs:
========================================================================== */