Visual Sense
本文总结的是 Applied Accessibility 中与视觉相关的内容
Make Elements Only Visible to a Screen Reader by Using Custom CSS
CSS's magic can also improve accessibility on your page when you want to visually hide content meant only for screen readers.
This happens when information is in a visual format (like a chart), but screen reader users need an alternative presentation (like a table) to access the data.
CSS is used to position the screen reader-only elements off the visual area of the browser window.
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通过调节对比度提高文本可读性
参考资料：
- Improve Readability with High Contrast Text
- Avoid Colorblindness Issues by Using Sufficient Contrast