Font Management

You can set the typeface for atom labels and text annotations, and add fonts beyond the five built-in system faces. The document records the fonts it uses, so they survive save and reload and carry into exports.

Where you choose a font

For atom labels, open Structure Settings and go to the Atoms panel. The Label Font dropdown sets the typeface for element symbols across the structure. The default is Arial; the list also includes Times New Roman, Helvetica, Georgia and Courier New, plus any fonts you have added.

For text annotations, use the font picker on the formatting toolbar while you edit the text. Each entry previews in its own typeface, and a Google font loads when you pick it.

The five system fonts (Arial, Times New Roman, Helvetica, Courier New, Georgia) are always available and need no setup.

Adding fonts

Both the Label Font dropdown (the + button next to it) and the annotation font picker open the Add Fonts dialog. It has two modes:

Google fonts

Search the curated Google Fonts catalog by name or browse by category (sans-serif, serif, display, handwriting, monospace). Typing a name also runs a live check against the Google Fonts API, so fonts outside the bundled list can still be found. When you add a Google font, Molkit injects a stylesheet link to load it; nothing is downloaded to your machine.

Local fonts

Switch to the Upload Font tab to add a font file from disk. Supported formats are .ttf, .otf, and .woff2. The file is stored in your browser (IndexedDB) and registered with an @font-face rule so it renders immediately. Local fonts are tied to the browser you uploaded them in.

Added fonts persist in your font library across sessions. To remove a user-added font, select it in the Label Font dropdown and click the × button; this also deletes a local font’s stored file.

Missing-font warnings

Molkit records which non-system fonts a document uses and saves that list with the file. When you open a file that references a local font missing from this browser, a status-bar notification appears reading Missing font: "<name>" with two actions:

Upload opens the Add Fonts dialog so you can supply the file again.
Substitute asks for a replacement name and swaps it across all atoms, annotations and structure settings. Leaving it blank falls back to Arial.

Google fonts referenced by a file reload automatically, so the warning is specific to local fonts that are not present.

How fonts reach exports

Before each save, Molkit scans the document for every non-system font in use and stores an accurate list.

How fonts travel depends on where the document goes:

SVG export: the Embed fonts for offline use option writes the fonts into the SVG. It is checked for you when the document uses a font you uploaded. See Font Embedding & Convert to Paths.
PNG and Copy as image: fonts are embedded automatically before the drawing becomes pixels.
PDF: the system fonts print in the PDF standard fonts, and Google fonts and uploaded TTF or OTF fonts are embedded automatically. An uploaded WOFF2 font cannot go into a PDF and prints in a standard font. Characters a font lacks, such as Greek letters, fall back to bundled fonts. See Font Embedding & Convert to Paths.
.mkit files: a file keeps the uploaded fonts it arrived with on every save, and in Firefox and Zen the Embed custom fonts in file option in the Save File dialog adds the rest. Opening a file that carries fonts adds them to your font library. See .mkit Files.