Make your Divi slider text easier to read by adding a semi-transaprent background to the slider. Just add the following CSS:

divi-slider-transparent-text.css

.et_pb_bg_layout_dark
.et_pb_slide_description {
  background-color: rgba(0,0,0,0.5);
  display: inline-block;
  padding: 50px;
  margin: 100px;
  border-radius: 15px;
  }