FWIW I’m running a Linux Mint 19 machine, I don’t recall seeing this problem prior to today; Saturday, 6-Apr-19. I have been visiting the SDMB for many years using Linux machines without experiencing this problem.
I experience this on SultanTheme if the zoom is too high. For my computer, 125% is the sweet spot where it fits. After that, it jumps and part of the page is cut off.
I hadn’t bothered trying to figure it out before, since I don’t use Advanced Search much, and, since no one mentioned the problem before, I never thought anyone zoomed in that far.
I had my zoom set to 200%, I reduced my zoom to 150% and can see all of the Advanced Search Page now. I still don’t know why I couldn’t drag the SDMB advanced search into view, but reducing the zoom proved to have a functionally similar effect.