I would like to build a mobile platform for my website. all the plug ins I have found simply optimise my main website for mobile devices (with a handful of customise options).

I would like a lot more customisation.

is there a builder I can use to build a mobile platform from scratch?

I have tried Duda mobile (you can build from scratch here) but its was a little buggy.

Your website will have some sort of “theme” or design section, that defines how to style all the output. You need to either use an already mobile-first theme that you can download for your website software (WordPress? Drupal? Joomla?) or design one yourself.

Rachel

I use the divi theme (elegant themes)