Layouts
There are various ways that you can create layouts in Arc. It's important to use these components correctly in order for everything to align correctly.
Section
The section component has a max width by default but can be set to be fluid. This is a good starting point to keep content and readable width's on larger screens.
Grid
The grid component has the same sizing as the section, but gives you powerful capabilities for creating column layouts. For example, you could have a section and a grid as direct siblings and they will align perfectly.
Columns
This is an older component that creates column layouts. These are best used within sections to maintain proper alignment, although, they can technically be used anywhere.
To ensure that layouts generally align well, use columns inside of sections, and use grids outside of sections.