Summation symbols, square roots, and infinity signs.
: This is a CSS issue. The webpage explicitly calls font-family: SymbolMTNormal, Symbol, "Arial Unicode MS" . You can install the font locally, but a better fix is to use a browser extension like "Font Changer" to map SymbolMTNormal to "Noto Sans Math" (a free, open-source math font). symbolmtnormal font free
Check your local font folder ( C:\Windows\Fonts ) for symbol.ttf . It is often already there if you use Microsoft Office . Summation symbols, square roots, and infinity signs