The Screeny Exposure! skin by AO3 

Exposes every heading, title, and name with the "landmark" class 
to the readers that can't read them
Role:
Media:
screen
Condition:
Normal

CSS

ul#skiplinks,
.landmark,
#outer .landmark,
.landmark a,
.index .heading.landmark {
  font-size: 100%;
  line-height: 1.5;
  height: auto;
  margin: auto;
  clear: both;
  color: #000;
  opacity: 1;
}