Theme

The app comes light or dark. The user chooses with the sun/moon toggle at the top of every screen, or under Appearance in the study preferences, where a third choice, "As my browser", follows prefers-color-scheme (and keeps following it as it changes). Until anything is chosen, that is what the app does.

Where the choice is kept

The diagram's source

flowchart LR
  accTitle: Where the theme is kept
  accDescr: A theme choice is kept on this device, and in the instance's preferences when one is open, which set the device's choice when the instance is opened.
  choose["A choice"] --> device["This device<br/>localStorage solid-memo:theme"]
  choose -->|"an instance is open<br/>and has preferences"| pod["preferences.ttl<br/>sm:theme"]
  pod -->|"the instance is opened"| device

• In the pod, as sm:theme in the instance's preferences (preferences format 4): a concept of sm:Themes (sm:systemTheme, sm:lightTheme, sm:darkTheme). This is the choice that counts, and it follows the user to every device. It is written once the instance has preferences, that is after the user's first save of the study preferences (which saves the theme shown at the time); before that, a choice is kept on the device alone.
• On the device, by the ThemePreference port (localStorageThemePreference.ts, key solid-memo:theme; "As my browser" is no key at all). It is what the sign-in screens and the first paint have, before any pod is reached. Opening an instance whose preferences say otherwise copies their choice here (instanceTheme).

A write to the pod that fails (another device saved the preferences meanwhile, say) is undone: the app reads the preferences back and shows what they hold.

Showing it

The stylesheet's dark colors hang off <html data-theme="dark">. A small script in apps/web/index.html (the page the Studio is in too) sets the attribute from the device's choice, else the browser's, before the first paint, so a page never flashes in the other theme; packages/ui/src/ui/theme.tsx takes over from there and also sets the theme-color meta tags for the browser's own chrome.

Korean text

Korean, on a Korean page or in card text marked lang="ko" on another, has its own :lang(ko) rules in style.css: Korean fonts (Apple SD Gothic Neo, Malgun Gothic, Noto Sans KR) ahead of the Japanese ones, which hold Hangul too but draw it with Japanese shapes and metrics; Fredoka and Bangers stay first for the Latin letters. Lines break between words, not syllables (word-break: keep-all). Headings, which Bangers cannot draw in Korean, are bold, and neither they nor the uppercase labels are tracked apart. Code, kbd, samp and pre keep the monospace font (--font-mono), which the Korean font rule would otherwise take from them.

Arabic text

Arabic in card text marked lang="ar" has its own :lang(ar) rules in style.css: Noto Naskh Arabic, a book hand that draws the vowel marks clearly, bundled like Fredoka (only its Arabic files are fetched, and only for Arabic text), after Fredoka for the Latin letters and before the systems' Arabic fonts (Geeza Pro, Segoe UI, Tahoma). Arabic letters join, so no Arabic text is tracked apart: not headings, not the card's question (tightened for Latin letters), not the uppercase labels. Headings, which Bangers cannot draw in Arabic, are bold in the Arabic font, and code keeps the monospace font, as in Korean. Arabic, like any language written right to left, runs right to left in its own isolated box (i18n.md).

German text

German, on a German page or in card text marked lang="de" on another, is hyphenated at line ends (hyphens: auto under :lang(de)), so a long compound word ("Wiederholungsintervall") breaks at a syllable with a hyphen rather than at any letter. Spanish and French need no rules of their own: Fredoka and Bangers draw their letters.