Squarespace webpage coding - Adapt banner to mobile phone screens

General information for the website: Management consulting firm homepage
Kind of development: Customization of existing website
Num. of web pages/modules: 1
Description of every page/module: www.konsert.com
Description of requirements/features: We have recently changed company name and updated our homepage (www.konsert.com). It is a squarespace page using the Bedford template.

On the new landing page, we use four pictures as a banner (sliders). The banner looks good at computer screens, but the banner size does not adapt to mobile screen format and resolution. The webpage’s preferred way is to have a background photo and overlay text that adapts to the screens. But we would like our visualizations (illustration + text) to be in the photos.

We would need help to add code to the page to control how the page displyas the banner on different screens (i.e. computer, ipad, mobile).
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