In a fresh installation of LibreOffice, cell backgrounds will not color in at all. This was the case both for a spreadsheet that had been created on Planmaker and also for a brand new spreadsheet created intially in Libre Office. On Windows 11. High Contrast not on. Problem is same whether on Windows dark mode or not. Also I cannot color characters in Calc. Can anyone suggest settings to change in Librecalc to correct this problem?
Responding to my own question: The problem is now solved, but I am not sure which step was crucial. In Tools>Options>Appearance, The L.O. Themes is Dark, matching Windows Dark apparently. But under the word Options on the same page, I see Light is selected in the radio button. Because the icons went so light, I also had to go to Tools>Options>View, and change Icon theme to Dark.