1. High Contrast Only

:root {
  --bg: #ffffff;
  --fg: #000000;
  --muted: #333333;
  --border: #cccccc;
  --link: #000000;
  --link-visited: #555555;
}

No dark mode. No gray-on-gray. Pure black on pure white.

2. Large Readable Type

body {
  font-family: serif;
  font-size: 20px;
  line-height: 1.6;
  max-width: 100%;
  padding: 16px;
  color: #000;
  background: #fff;
}

Serif reads better on e-ink. Minimum 18px, preferably 20px.