We’ve had some feedback that relying only on luminosity and position to
differentiate between the ‘will get alert’ and ‘likely to get alert’
areas on the map might not be enough.
We don’t want to introduce another colour because:
- it will make the map look very busy
- not many other colours contrast with the map tiles as well as blue
- relying on colour only to communicate information is also bad for
accessibility
Instead we can make one of the lines a different style. I’ve gone for
dashed on the ‘likely’ line because it looks nice, and gives some
suggestion of a porous boundary.
Implementing this means using CSS border image, because a `dashed`
border (which we still have as a fallback) doesn’t render with
consistent dash sizes from browser to browser. We need consistency to
match the dashes that the map will be drawing (which use SVG not CSS
so don’t have the same problem).
To help people understand that broadcasting is not a precise technology,
we have shown the estimate bleed area on the map.
Because people aren’t familiar with the technology a visual only clue is
not enough. So this commit adds a key to the map, which explains what
the different outlines mean.
It also removes the sticky footer from this page to:
- make the key visible on the page
- make people scroll and review the map before they get to the big green
button
- not reduce the size of the map any further
