tartinons

Hello, I am a new bigbox user. and i have problems with theme. I wanted to install the theme 21/9 but I encounter bugs. this one : I do not have the selection arrow that appears as on the video, and on the game pages I have a black background, the image seems to be on the right side of the theme rather than left. Do I miss something for the theme function? Some screenshot of my bigbox : No arrow : Black background on left, and the game picture is on right part of the screen behind the wheel (not like the video ? ) Do you know what I miss? Thanks ?