:root{
  --paper:#f5f6f4;--ink:#0f1d2e;--sub:#56626f;--rule:#d3d9dd;
  --flow:#0a7c76;--flow-bg:#e2f1ef;--heat:#d9480f;--heat-bg:#fbe9df;--grid:#e3e8ea;
}
@media (prefers-color-scheme:dark){:root{
  --paper:#0d141c;--ink:#e7ecf0;--sub:#93a0ac;--rule:#26323e;
  --flow:#3fc2b8;--flow-bg:#10302e;--heat:#ff8a50;--heat-bg:#3a2013;--grid:#17212b;
}}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:16px}
body{margin:0;background:var(--paper);color:var(--ink);font-family:"Zen Kaku Gothic New","Hiragino Sans","Yu Gothic UI","Yu Gothic",Meiryo,sans-serif;font-weight:500;line-height:1.95;font-size:17px;-webkit-text-size-adjust:100%;font-feature-settings:"palt"}
a{color:var(--flow);text-underline-offset:.2em}
a:focus-visible,summary:focus-visible{outline:3px solid var(--flow);outline-offset:3px}
.page{max-width:1040px;margin:0 auto;padding:0 20px}

/* header */
.site-header{border-bottom:1px solid var(--rule)}
.site-header .page{display:flex;align-items:baseline;justify-content:space-between;height:56px;align-items:center}
.site-header a{color:var(--ink);text-decoration:none;font-weight:900;font-size:1rem;letter-spacing:.04em}
.site-header span{color:var(--sub);font-size:.82rem}

/* title block */
.head{padding-top:44px;padding-bottom:8px}
.head h1{font-size:clamp(1.9rem,4.6vw,3.1rem);line-height:1.35;font-weight:900;margin:0 0 18px;max-width:20em;letter-spacing:.01em}
.head .meta{color:var(--sub);font-size:.88rem;margin:0}

/* hero figure */
.hero-fig{margin:28px 0 0}
.duo{display:grid;grid-template-columns:1fr 1fr;gap:0;border-top:2px solid var(--ink);border-bottom:1px solid var(--rule)}
.duo svg{display:block;width:100%;height:auto}
.duo svg+svg{border-left:1px solid var(--rule)}
@media (max-width:720px){.duo{grid-template-columns:1fr}.duo svg+svg{border-left:0;border-top:1px solid var(--rule)}}
.hero-fig figcaption{font-size:.82rem;color:var(--sub);margin-top:10px;line-height:1.7}
.t-h{font-size:22px;font-weight:900;fill:var(--ink)}
.t-s{font-size:14px;fill:var(--sub);font-weight:500}
.t-v{font-size:17px;font-weight:900}
.sheet{fill:url(#grid);stroke:var(--ink);stroke-width:1.5}
.tabbox{fill:var(--ink)}
.edge{stroke:var(--flow);stroke-width:7;stroke-linecap:butt}
.path-h{stroke:var(--heat);stroke-width:2;fill:none}
.path-f{stroke:var(--flow);stroke-width:2;fill:none}
.ahh{fill:var(--heat)}.ahf{fill:var(--flow)}
.dot{r:6px;offset-rotate:0deg;animation-name:go;animation-timing-function:linear;animation-fill-mode:both;animation-iteration-count:3;animation-delay:.5s}
.dot.h{fill:var(--heat)}.dot.f{fill:var(--flow)}
@keyframes go{from{offset-distance:0%}to{offset-distance:100%}}
@media (prefers-reduced-motion:reduce){.dot{animation:none;offset-distance:100%}}

/* body layout */
.cols{display:grid;grid-template-columns:200px minmax(0,680px);gap:56px;padding-top:48px;padding-bottom:24px}
@media (max-width:960px){.cols{grid-template-columns:1fr;gap:0;padding-top:28px}}
.toc{position:sticky;top:20px;align-self:start;font-size:.88rem;line-height:1.7}
.toc summary{font-weight:900;cursor:pointer;padding:6px 0;list-style:none}
.toc summary::-webkit-details-marker{display:none}
.toc ol{list-style:none;margin:8px 0 0;padding:0;border-left:2px solid var(--rule)}
.toc li a{display:block;padding:5px 0 5px 14px;color:var(--sub);text-decoration:none;margin-left:-2px;border-left:2px solid transparent}
.toc li a:hover{color:var(--ink);border-left-color:var(--flow)}
@media (max-width:960px){.toc{position:static;margin-bottom:28px;border-top:1px solid var(--rule);border-bottom:1px solid var(--rule);padding:6px 0}.toc summary::after{content:" +";color:var(--sub)}.toc[open] summary::after{content:" −"}}

article{max-width:680px}
article p{margin:1.1em 0}
article strong{font-weight:900}
.answer{font-size:1.32rem;line-height:1.75;font-weight:900;margin:0 0 1.4em;padding:0 0 1.2em;border-bottom:1px solid var(--rule)}
.answer em{font-style:normal;color:var(--flow)}
article h2{font-size:1.55rem;line-height:1.5;font-weight:900;margin:3em 0 .5em;padding-top:.9em;border-top:2px solid var(--ink)}

/* two laws */
.laws{display:grid;grid-template-columns:1fr 1fr;margin:1.6em 0;border-top:1px solid var(--rule);border-bottom:1px solid var(--rule)}
.law{padding:18px 20px 18px 0}
.law+.law{padding:18px 0 18px 22px;border-left:1px solid var(--rule)}
@media (max-width:600px){.laws{grid-template-columns:1fr}.law+.law{border-left:0;border-top:1px solid var(--rule);padding-left:0}}
.law .k{font-size:.8rem;color:var(--sub)}
.law .eq{font-size:1.5rem;font-weight:900;line-height:1.4;margin:.1em 0 .3em}
.law .eq b{color:var(--heat)}
.law p{margin:.3em 0;font-size:.95rem;line-height:1.85}

/* table */
.table-wrap{overflow-x:auto;margin:1.4em 0}
table{border-collapse:collapse;width:100%;font-size:.95rem}
th,td{padding:.7em .6em .7em 0;text-align:left;border-bottom:1px solid var(--rule)}
thead th{border-bottom:2px solid var(--ink);font-size:.82rem;color:var(--sub);font-weight:700}
td:last-child{font-weight:900}

/* 70 degrees */
.reading{display:flex;align-items:baseline;gap:20px;flex-wrap:wrap;background:var(--heat-bg);border-left:6px solid var(--heat);padding:18px 22px;margin:1.6em 0}
.reading .num{font-size:3rem;font-weight:900;line-height:1.1;color:var(--heat);white-space:nowrap}
.reading p{margin:0;font-size:.95rem;line-height:1.8;flex:1 1 260px}

/* faq */
.qa{border-top:1px solid var(--rule);padding:16px 0}
.qa:last-of-type{border-bottom:1px solid var(--rule)}
.qa h3{font-size:1.05rem;margin:0 0 .3em;font-weight:900;line-height:1.6}
.qa p{margin:.3em 0 0;font-size:.97rem}

/* summary */
.points{list-style:none;padding:0;margin:1em 0}
.points li{padding:.7em 0 .7em 2em;border-top:1px solid var(--rule);position:relative}
.points li:last-child{border-bottom:1px solid var(--rule)}
.points li::before{content:"";position:absolute;left:.2em;top:1.35em;width:.9em;height:.5em;border-left:3px solid var(--flow);border-bottom:3px solid var(--flow);transform:rotate(-45deg) translate(0,-50%)}
.next{color:var(--sub);font-size:.95rem}

/* sources */
.src{font-size:.85rem;line-height:1.8;color:var(--sub);padding-left:1.2em;margin:.6em 0}
.src li{margin:.7em 0;word-break:break-word}
.disclaimer{font-size:.82rem;color:var(--sub);margin-top:2em}

/* top page */
.lead{font-size:clamp(1.1rem,2.2vw,1.35rem);line-height:1.85;max-width:30em;margin:0;font-weight:500}
.list{margin:40px 0 0;border-top:2px solid var(--ink)}
.post{display:grid;grid-template-columns:140px 1fr;gap:8px 28px;padding:22px 0;border-bottom:1px solid var(--rule);text-decoration:none;color:var(--ink)}
@media (max-width:600px){.post{grid-template-columns:1fr}}
.post .area{font-size:.85rem;color:var(--sub);padding-top:.3em}
.post h2{margin:0;font-size:1.3rem;line-height:1.5;font-weight:900;border:0;padding:0}
.post p{margin:.3em 0 0;color:var(--sub);font-size:.93rem;line-height:1.8}
.post:hover h2{color:var(--flow);text-decoration:underline;text-underline-offset:.2em}

footer.site{border-top:1px solid var(--rule);margin-top:48px;padding:28px 0 48px;color:var(--sub);font-size:.82rem}