Run these lines one at a time in SSH and see if it fixes your issue.
cd /emuelec/bin
wget https://raw.githubusercontent.com/EmuELEC/EmuELEC/4084e7d281c1f842b6290c288ecb20501c126629/packages/sx05re/emuelec/bin/setres.sh
chmod +x setres.sh
echo "ee_videowindow=10 5" >> /emuelec/configs/emuelec.conf
Then reboot.
The older setres.sh may have a bug in it. This uses the latest setres and the last line fixes up bordering issues for 480cvbs.