[Add] loader to the game and new css file

[Rafajrg21]

What does this PR do?

This PR adds a new loader function and loader element to the project which is shown during the loading of the game. I also created a new styles.css file because the styles were getting a little too big for comfort. Any feedback or correction is appreciated

Screenshots of changes made to the webapp.

Related PRs and Issues

This PR solves #93

Have you updated the README.md file?

• [ ] yes
• [x] no

Have you made any big breakthrough change?

• [ ] yes
• [x] no

Is the code beautified?

• [x] yes
• [ ] no

Is the code clear to understand with proper variable naming and comments?

• [x] yes
• [ ] no