[ivorb]

What

• Save in this browser on convert.html. The original .pptx is stored in IndexedDB and converted again when opened (under a second). Saved decks are listed with Open / Remove / Remove all and a size total, and stay until removed or site data is cleared. They never leave the browser and are not synced. Requests persistent storage so the browser is less likely to evict them.
• Fix: text color lost after closing the preview. Reveal's theme restyled the converter page's body; the preview now runs in its own iframe (with fullscreen allowed).

Checked

Browser test with a 15 MB, 44-slide deck: text color unchanged after preview; save, then clearing tab storage and reloading still lists it; Open reconverts it; Remove all clears it. node --test: 37 pass.