Insights page accessibility issues

[sveltifier]

1. Check colour contrast ratios. 3:1 ratio required.
2. Figure out a sensible text alternative to the charts. Sould be adequate to say the value and the median. SVG could be marked up as a figure role="presentation" with an alt text.
3. Make sure that (i) buttons have a proper label and that the expand has a suitable aria label on it.
4. Fading behaviour on hover not ideal.
5. Clicking nav links is not moving focus to the new section.
6. Make sure that alternatives to charts are properly signposted.