The file in question is
/usr/share/dump1090-fa/html/style.css
Try
sudo nano /usr/share/dump1090-fa/html/style.css
CTRL-O to save and CTRL-X to exit
The file in question is
/usr/share/dump1090-fa/html/style.css
Try
sudo nano /usr/share/dump1090-fa/html/style.css
CTRL-O to save and CTRL-X to exit