Acid1

Acid1, also known as Acid1 test or the Box acid test, is a website designed to test the compliance of web browsers with the Cascading Style Sheets (CSS) 1.0 standard. Created by Todd Fahrner in 1998, it was one of the first comprehensive tests to verify how well browsers rendered CSS properties. The test consists of a single HTML page and a linked CSS stylesheet that together attempt to exercise a wide range of CSS features, including selectors, properties, and values.

The Acid1 test became a benchmark for browser developers, influencing the implementation of CSS in popular browsers like Netscape Navigator and Internet Explorer. By achieving a passing score on Acid1, a browser demonstrated a significant level of adherence to the CSS 1.0 specification. Its success led to the development of subsequent tests, such as Acid2 and Acid3, which tested newer versions of CSS and other web standards. While largely superseded by newer, more rigorous tests, Acid1 remains historically significant for its role in promoting web standards compliance and improving the visual rendering capabilities of early web browsers.