HubSpot's modules work on a flexible grid that automatically adjusts their proportions to fit a viewer's screen dimensions. This responsive system relies on percentage widths and heights to make a smooth transition between devices.
When a module, column, or wrapper is set to use fixed widths or heights this responsiveness is broken and the page will no longer fluidly adjust the size of your content to fit the viewer's device. To prevent your layout from breaking on mobile devices, any styling on your pages for height and width attributes should be done with min/max width in percentage format.
You can learn more about where the styling on your page might be coming from in this article. Please note that if you are not comfortable reading or editing CSS, it is highly recommended that you work with a designer to make edits to your website's styling. You can find HubSpot partners who can help with website design here.