<!DOCTYPE html><html lang="en-US"><meta name="keywords" content="Chinese calendar, Shangyuan, superior epoch, calendar calculation"><meta charset="UTF-8"><meta name="viewport" content="width=device-width,initial-scale=1"><head><title>Shangyuan Astronomical System</title><link rel="stylesheet" href="calendar_min.css"><style>body{counter-reset:sec-counter}sect{counter-reset:subsec-counter}sect::before{counter-increment:sec-counter 1;content:counter(sec-counter) ". "}subsect::before{counter-increment:subsec-co