body { background: black; color: white; font: sans-serif 14pt; }
a { color: lightblue; } a:hover { color: white; background: blue; }
table, tr, td, th { border-collapse: collapse; padding: 0.25em 0.5em; border: solid 1px; }
li > pre:empty::after { content: "(empty)"; opacity: 0.25; }
:is(tr, ul > li[id], details > summary:hover):hover { background-color: #fff2; }
pre, code { font-size: inherit; font-family: monospace, monospace; }
pre { font-size: 16pt; } pre:lang(ja) { font-size: 18pt; }
details { display: inline-block; margin: 0.5em 0.25em; border: solid 1px; border-radius: 1em; }
details > summary { display: block; margin: 0; padding: 0.5em; cursor: pointer; }
details > summary > :is(h2, h3, h4) { margin: 0; }
details > summary > :is(h2, h3, h4)::before { content: "+ "; }
details:open { display: block; }
details:open > summary > :is(h2, h3, h4)::before { content: "\2212  "; }
em { font-style: normal; }
em.c1 { color: red; }
em.c3 { color: blue; }
em.c4 { color: gold; }
em.c6 { color: orangered; }
em.c7 { color: springgreen; }
em.c8 { color: royalblue; }
em.c9 { color: orange; }