This are the options i passed, i added slider-prev for previous same slider-next for next but not working
options={{ type: 'slide', arrows: false, pagination: false, classes: { prev: 'slider-prev', next: 'slider-next', }, }}
I tried this as well add slider-arrow common class here as well
options={{ type: 'slide', arrows: false, pagination: false, classes: { prev: 'slider-arrow slider-prev', next: 'slider-arrow slider-next', }, }}
Here, what you did it completely added custom classes for arrow and how this will work is, these classwa will totally replace with default splide slider classes. and to solve this or to add default css, you also need to pass that default class with your custom class.
and For your case it will be like