The amount of local storage needed for this guide is quite reasonable on modern devices, but it is still an intense experience for some browsers. Hopefully these notes will prevent frustration on your end.
I believe that Firefox’s support has improved since I first wrote these notes in 2020, but I haven’t tested Firefox extensively since then.
Downloading files for local offline use will continue in the background while you browse the guide (including this page). However, downloading is likely to pause in any of the following cases:
If the downloading process is paused, just click the green button again to resume.
On a desktop, it should be sufficient to keep the Guide tab visible (not minimized), even if another window has focus.
The Guide is fairly large, but should fit easily in a reasonably modern phone.
Recent versions of Firefox seem to allow the Guide to use more device space than previous versions. However, if Firefox doesn’t allow enough space, you might need to use another browser with a less restrictive limit.
Firefox on the desktop may ask whether to allow the Guide to store data in persistent storage. If you respond with “Not now” or “Never”, the files will still be recorded locally, but the browser may delete them later if space runs short. If you respond with “Allow”, all local Guide files (including files downloaded previously) will be kept until you actively delete them. Oddly, persistent local files don’t fully count toward quota usage. The Guide therefore estimates the actual storage consumption.
As far as I can tell, Firefox on mobile does not yet support persistent storage. In practice, as long as you use the Guide occasionally, Firefox is unlikely to delete its offline files.
If you’ve read down this far, congratulations. You might be the kind of person who runs their browser in Private Browsing mode. Firefox doesn’t allow any interaction with local files while in Private Browsing mode. You’ll need to disable Private Browsing in order to download or use local files.
You can save a link to the Guide on your home screen. On Android, open the Firefox menu and select “Install.” Sometimes this doesn’t actually put anything on your home screen. If so, you can manually drag it from Android’s installed apps to your home screen.
Firefox on iOS or the desktop doesn’t offer an installation option. Sorry. As an alternative, you can bookmark the Guide for use in offline mode.
Because of the strange way that browsers work, every page load will attempt to fetch ~25 KB from the internet even when the site is using its local offline copy. (E.g. viewing 40 pages will fetch ~1 MB.) If you have a large or unlimited data plan, this is nothing to worry about. If you have a very limited data plan, consider putting your phone in airplane mode while using the site in offline mode.
Of course, external links will still fetch from the internet as usual. Most external links are styled and colored in the usual way for your browser (e.g. blue and underlined). Links to Jepson are in orange, and also must fetch from the internet. Placeholder boxes that link to photos at CalPhotos or Calflora are also external links. By contrast, internal links to taxons are colored brown, green, or black and use the offline copy, as do all links from a thumbnail image to the full-sized image. A few miscellaneous internal links (not to a taxon) are also in the default browser style.
Return to the Guide home and give offline mode a try. If it doesn’t work, online browsing remains supported as always.