From relevant Wikipedia page in Chinese: "因为最流行的版本用红色封面包装，文化大革命中通称「红宝书」
Which translates to: “Because the most popular version had a red cover, it was commonly known as the “Little Red Book” during the Cultural Revolution.”
Edit: typo
Windows 11 as my everyday os
But everything around me is Linux (proxmox running Debian LXC) or BSD (opnsense, truenas)
From relevant Wikipedia page in Chinese: "因为最流行的版本用红色封面包装，文化大革命中通称「红宝书」
Which translates to: “Because the most popular version had a red cover, it was commonly known as the “Little Red Book” during the Cultural Revolution.”
Edit: typo