Great work overall Daliz. Here are a couple of notes I would advise.
Show - we have a show route and our functionality is here. I'd recommend doing the flex feature and adding a show route to your frontend.
React.Fragment - nice use of the new React.Fragments. You can also write a fragment as <> or </> in React but currently its not supported everywhere so using React.Fragment is more responsible way to wrap our JSX without a div.
CSS - Great job with React Bootstrap. I also commend the use of styled-components.
Navbar.Item - I would recommend moving your Nav.Link components to a new line . It makes them easier to read as separate from their parent component.
TransacitonNewForm - We're using <br /> tags to make space in our form. Using CSS is a better option.
Great work overall Daliz. Here are a couple of notes I would advise.
<>or</>in React but currently its not supported everywhere so using React.Fragment is more responsible way to wrap our JSX without a div.styled-components.Nav.Linkcomponents to a new line . It makes them easier to read as separate from their parent component.<br />tags to make space in our form. Using CSS is a better option.