Hi el-profe
You will need to change in LESS file:
/templates/ja_teline_v/less/variables.less
At approx line 690, look for this code:
// Container sizes
// --------------------------------------------------
// Small screen / tablet
@container-tablet: ((720px + @grid-gutter-width));
@container-sm: @container-tablet;
// Medium screen / desktop
@container-desktop: ((940px + @grid-gutter-width));
@container-md: @container-desktop;
// Large screen / wide desktop
@container-large-desktop: ((1140px + @grid-gutter-width));
@container-lg: @container-large-desktop;
For desktop, you can increase value for the variable: container-large-desktop
After changing this less file, you need to go to Backend >> Extensions >> Templates >> JA Teline V, then hit the button LESS >> CSS to compile less to css.
But REMEMBER to backup all CSS files on your site first as it will override current css files when compiling.
Regards