main.js uses 4 spaces for indents

[peterVG]

It it Javascript best practice to use 2 spaces for indents as enforced by most linters (eg. ESlint, StandardJS, Prettifier). Since this is a beginner tutorial, it's helpful to start us off with good habits.

[Sn3akyP3t3]

ESlint documentation acknowledges the existence of other acceptable style guides per https://eslint.org/docs/latest/rules/indent. Its probably just best then to adopt whichever of those acceptable styles makes you happy or just adopt the one that your linting tool prefers.