[BUG] Unrecognizable functionalities when font is not loaded

[fwjmath]

When remote fonts are not loaded (due to network problem or protective plugins), it is not possible to know the functionnality of some of the buttons on the site.

Reproduction Steps to reproduce:

1. Install Firefox
2. Install uBlock Origin plugin for Firefox, which disables remote fonts by default
3. Go to the site, look at the button icons on top.

Expected Behavior The buttons should all be either tofu (unrecognized UTF8 characters) or exotic characters, as the font is not loaded, but there should be fall-back (such as alt-text) that indicates the functionnalities of buttons.

Actual Behavior No indication is given for the buttons.

Environment Browser(s): Firefox with uBlock Origin Operating System: Xubuntu 20.04