LO Calc stared up in dark theme. I want to revert back to light theme but under Tools/Options/View I can only change Icons. Where is the overall theme changed?
In Tools - Options - LibreOffice - Appearance either create a New theme or click the icon with tooltip Add more themes , select one of the preset themes and click install. Select the preset theme from the drop down and allow LibreOffice to restart.
25.2 has new appearance settings and work is ongoing to fix the bugs. I find the preset Office 2003 Blue OK for light and dark display for the moment.
Best not to play with the System, Dark, Light settings for now.
Look under Tools/Options/Appearance