Stella

Cards

Data model

  • Group: an optional folder for decks. A deck belongs to at most one group.
  • Deck: a named collection of facts (name up to 32 characters, description, optional cover image, optional group).
  • Tag: a free label; a deck can carry any number of them, independent of groups.
  • Fact: the content itself, a front and a back, plus an optional image and audio file per side. A fact belongs to one deck.
  • Card: one direction of quizzing derived from a fact. The forward card (front → back) always exists; the reverse card (back → front) is optional and needs a non-empty back.

Groups are one per deck (exclusive categories); tags are many per deck (cross-cutting labels).

Content format

Front and back are Markdown, hard-wrapped (one newline in the source is one line break on the card), with Stella’s own inline syntax on top. Raw HTML is never passed through. All of these can be mixed within a side:

SyntaxRenders asNotes
**bold**, *italic*, # heading, - item, 1. item, [text](url)Normal Markdown
{#RRGGBB}text{/}Colored textThe hex must be exactly 6 digits
{base|reading}Ruby/furigana, e.g. {漢字|かんじ}No braces, pipes or newlines inside; doesn’t nest
{tts:en}text{/tts}, {tts:ja}text{/tts}A read-aloud button plus the text (browser speech synthesis, no audio file needed)Only en and ja; the closing tag is {/tts}, not {/}
{center}...{/center}A centered blockSides are justified by default. A color, tts or furigana span can’t straddle the boundary: nest it inside
$formula$Inline math (KaTeX)No $ or newline inside
$$formula$$Display math (KaTeX)May span lines

For example:

{center}What is the Pythagorean theorem?{/center}
{center}$$a^2 + b^2 = c^2$$

For a right triangle with legs $a$, $b$ and hypotenuse $c$.{/center}
{center}This combines **everything**: {#22aa55}color{/}, {tts:en}speech{/tts}, and {漢字|かんじ} furigana.{/center}

Plain-text clients, like the e-ink sync device, get all of this stripped to bare text: furigana becomes base（reading）, and every other construct is unwrapped to its inner content.

Media

Each side can carry one image (jpg, png, gif, webp) and one audio file (mp3, ogg, wav, m4a, webm, aac, flac). With cards.autoplayAudio on, audio plays as soon as its side is shown.

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