===Background
With the upcoming [[ https://phabricator.wikimedia.org/T300673 | changes to the main menu ]] and article tools, modern Vector will likely need to accommodate what is essentially a responsive 3 column layout. Our current markup/CSS relies heavily on floats and margins, and it has already been difficult to maintain with different screen sizes. Moving towards a grid system would allow us to greatly simply our CSS.
An example of what Vector's grid could look like:
| header | header | header |
| sidebar | article tools | column |
| sidebar | content | column |
| sidebar | content | column |
| sidebar | content | column |
| | footer | |
===AC
An unmerged patch exists that does the following:
[] Vector uses a flexbox or CSS grid based grid
[] Markup is updated to reflect new grid system, this includes moving the article tools header
[] No visual change
== Sign off steps
[] Work out next steps for making this a reality.