fix styles for Readme and image details secions

[Roshanjossey]

PR checklist

Please tick all of the below (if a certain item is not required for this PR please tick the box anyway)

Docs

• [ ] If you added new code; is it self documenting? (all the variable names clear, comments added where appropriate)
• [ ] If you touched existing code; did you refactor existing naming, added comments where necessary?

Tests

• [ ] If your ticket adds new functionality; have you added unit tests to verify behaviour?
• [ ] If your ticket alters user interaction with the UI; have you added integration tests?
• [ ] Do your tests check for every convievable user behabviour? (all behaviours the user can perform)

Typing

• [ ] If you added new code; have you added typing?
• [ ] If you touched existing code; have you improved its typing?

Styling

• [ ] If new styles were created; Did you refactor/add more styles in css-in-js style?
• [ ] Are all fonts, sizes, colours, margins, paddings in line with designs?
• [ ] Did you perform a visual comparison of the implementation with the designs?

[codecov[bot]]

Codecov Report

Merging #329 (0d04908) into master (2972d6c) will increase coverage by 0.16%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #329      +/-   ##
==========================================
+ Coverage   66.85%   67.01%   +0.16%     
==========================================
  Files          62       62              
  Lines        1439     1446       +7     
  Branches      218      218              
==========================================
+ Hits          962      969       +7     
  Misses        477      477              

Impacted Files	Coverage Δ
src/redux/hub/hub.selectors.ts	100.00% <100.00%> (ø)
src/theme.ts	100.00% <100.00%> (ø)

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