Minimal coverage of CSS files

[jamessspanggg]

Problem:
When using Coverage tab in Chrome dev tools to analyse the coverage of our CSS and JS files, it is shown that we are utilising vue-loading-spinner.css and mui.min.css in a small percentage.

Running audits in the Chrome dev tools also shows that there will be potential savings in loading time if we remove both css files.

Suggestion:
Since we are using only a small part of these two files, let's remove the importing of these files and create our own css classes that achieves the style required.

[Tejas2805]

@jamessspanggg the usage of mui.min.css has increased. Do let me know if you still want me to create our own css class for this style.

[jamessspanggg]

@Tejas2805 it may be better to focus on other issues as this issue may not be as critical.

[Tejas2805]

@jamessspanggg I have already worked on removing the vue-loading-spinner.css. So maybe I will just do a pull request for that for the time being?

[ckcherry23]

Related to #1718