Improve usage of UI space
I've modified the CSS to make better use of existing space and minimize the use of scrollbars for charts:
- The main content is now wider.
- On a 1080 screen, the charts should only overflow with zoom over 120%.
- Scrollbars are still needed on resolutions between ~1100 and ~1600 (narrow, two-column layout).
The charts, despite being SVG, are currently not scalable. To have the charts scale to the size of the widget, we'd need to revisit the code that generates them, which I wanted to avoid in this case.
Bug: T377871