Restyle the Slides

## Do you have an eye for design?
Help us improve the look of the slide deck.
If you need help, check out the Appendix in the training manual.

Start by reviewing the existing slide deck and the Appendix in the training manual for the intended visual guidance. Identify the deck assets and current styling before proposing changes. Done means the slides have a consistently improved appearance, with the result checked across the full deck.

索引モデルが issue の本文から書いたものです。