fix margins between slides and view all chapters button

[hxdy-1]

PR Fixes:

• 1 Added margin between "Slides" and "View all chapters" button
• 2 Removed unnecessary
  and added margins for better spacing

Resolves #418

Checklist before requesting a review

• [x] I have performed a self-review of my code
• [ ] I assure there is no similar/duplicate pull request regarding same issue