Site on landscape view for mobile shows desktop ver of site rather than stacked ver

Hoping to get some assistance with my site - I've noticed that whenever it goes into landscape view for any devices (phone + tablet), the site will show the desktop ver of the site, which has the sidebar navigation that takes a up a large portion of the page and maintains the columns for certain pages (ie. Within the Upper Bay keeps the 3 column format from the desktop ver). Wondering if there is a way to adjust the breakpoint / code a fix so that the landscape view on devices just shows the same stacked view w/ mobile nav as portrait view, while keeping the desktop ver for larger screens as is?

Note: This site is built on 7.0 and with Wells family template
Site: https://www.nlindt.com/