fix(cash register): styles, allow large browser font sizes

[lasjorg]

Checklist:

• I have read freeCodeCamp's contribution guidelines.
• My pull request has a descriptive title (not a vague title like Update index.md)

Related: freeCodeCamp/freeCodeCamp#55542

Updated the styles:

• Allow for large browser fonts without an overflow
• Avoid unnecessary text wrapping by giving it more width, but having a min width on body at 320px

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I only tested this locally using the HTML/CSS, I didn't run the repo.