Hi,
This template is built with Bootstrap, you can change the width of container size in the LESS file: root/templates/ja_teline_v/less/variables.less
// 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;