Coding Bootcamp Testimonials Slider using Gatsby

Do you have suggestions to better style the buttons and shadows as shown in the design?

Just some info: I didnt use Gatsby Plugin image due to the bad resolution of responsive design by the helper function with-art-direction. Instead I used a styled div which worked better for me. For the slider I used bootstrap react carousel which I can really recommend, its easy to style and you dont need much additional Java Script.