Just so that I never lose these

The general ranges of width for each device are as follows:

Large Desktop: 1405px and above
Standard Desktop: between 1100px and 1405px
Laptops and Large Tablets: between 980px and 1100px
Tablets: between 768px and 980px
Smartphones and small Tablets: between 320px and 768px;
Smartphones: between 320px and 480px;

Here is a list of the main media queries used in the Divi Theme. You can use this as a helpful template for your custom CSS.

Kudos to the original blog post by Elegant Themes https://www.elegantthemes.com/blog/divi-resources/how-to-identify-divis-responsive-breakpoints-and-fine-tune-your-designs-with-media-queries