Make overview spacings dynamic and tweak them

Tweak the spacings in the overview and make them dynamic, so that they work well across all common screen sizes, and to allow the dash to use a larger icon size.

Compared to main on most popular screen resolutions (ordered by market share, together those make up about 60-70% of the desktop resolutions globally):

1920x1080 (~25% worldwide)

main:

new:

1366x768 (~15% worldwide, top resolution in africa, south america, india)

main:

new:

1536x864 (~10% worldwide)

main:

new:

1440x900 (~5% worldwide)

main:

new:

1280x720 (~5% worldwide)

main:

new:

1024x768 (most popular tablet resolution)

main:

new:

bonus: 720x360 (most popular phone resolution)

main:

new: