Mobile page layout improvements

[Aloso]

On mobile, the editors are stacked vertically which is usually a good idea. However, the editors intercept touch events making it impossible to scroll the page (not just the editor) by swiping with a finger.

I propose to show a tab bar on mobile instead, with 3 tabs: "Gleam", "Result", "Compiled JS/Erlang". When pressing the "Build & Run" button, the "Result" tab should be opened automatically.

[inoas]

I have added padding to the sides to allow scrolling, but yes, that was just a quick workaround.