Gallery arows customization?

Site URL: https://www.flexpenser.com/

How can I change the color of gallery slide show full arrows in Squarespace, also how to remove the arrows background?

Feel free to try

section[data-section-id="5ee3a848a176cf4b8b654938"] .gallery-fullscreen-slideshow-control-btn {
  background-color: transparent;
}
section[data-section-id="5ee3a848a176cf4b8b654938"] .gallery-fullscreen-slideshow-control-btn-icon svg {
  background-color: transparent;
}
section[data-section-id="5ee3a848a176cf4b8b654938"].light .gallery-fullscreen-slideshow-control-btn::before, section[data-section-id="5ee3a848a176cf4b8b654938"].light .gallery-slideshow-control-btn::before {
  background-color: transparent;
}
/* Section background if you want to change */
section[data-section-id="5ee3a848a176cf4b8b654938"].light:not(.has-background) .section-background {
    background-color: #FFC107;
}

Place it into  Design -> Custom css

Thank you. But, this does does not wok.

1 hour ago, Kewmars said:

Thank you. But, this does does not wok.

That strange, could you invite me as collaborator to check