Looks like a bug in their light theme - it's using the dark theme's background. There's a theme toggle top-left to switch to the still-functioning dark theme.
Guessing they probably started with a light theme then retrofitted a dark theme & rolled it out without realising it would regress the existing light theme.
Guessing they probably started with a light theme then retrofitted a dark theme & rolled it out without realising it would regress the existing light theme.