Task - Refactoring Stylings

[franziska-caroline]

Tasks

• [ ] outsource all repetitive elements (e.g. the back button) into own components
• [ ] consistent styling
  • [ ] check that all buttons and cards have the same border radius
  • [ ] font sizes, weights, etc
  • [x] placement of the favorite button button on the detailspage
  • [x] the back button could look better (the arrow is not centered)
  • [ ] Design for different browsers
  • [x] on the Journal Details page only show the headings and text fields if they have been filled in the form ( XY > 0 ? : )