:root{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans JP",Meiryo,sans-serif;color:#162b35;background:#fff;line-height:1.85;font-size:16px;--ink:#162b35;--muted:#546774;--line:#dce4e6;--accent:#b73b16;--panel:#f0f5f6;--blue:#12536a}*{box-sizing:border-box}body{margin:0}a{color:var(--blue);text-underline-offset:.22em}a:hover{text-decoration-thickness:2px}a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible,[tabindex]:focus-visible{outline:3px solid #c85216;outline-offset:4px}h1,h2,h3,p{margin-top:0}h1,h2,h3{line-height:1.45;letter-spacing:.01em}h1{font-size:clamp(2rem,4.5vw,3.8rem);margin-bottom:24px}h2{font-size:1.65rem;margin-bottom:20px}h3{font-size:1.2rem}p{margin-bottom:1.2rem}.wrap{width:min(1120px,calc(100% - 64px));margin:auto}.small{font-size:.875rem;color:var(--muted)}.skip{position:absolute;top:-200px;left:16px;z-index:10;padding:8px 16px;background:white}.skip:focus{top:8px}.masthead{border-bottom:1px solid var(--line)}.masthead .wrap{min-height:92px;display:flex;align-items:center;justify-content:space-between;gap:24px}.brand{font-size:1.55rem;color:var(--ink);font-weight:800;text-decoration:none;display:flex;align-items:center;gap:13px;white-space:nowrap}.brand-icon{width:29px;height:27px;border:2px solid var(--accent);border-radius:3px;position:relative}.brand-icon:before{content:"";position:absolute;left:-5px;top:-6px;width:35px;height:2px;background:var(--accent)}.brand-icon:after{content:"";position:absolute;left:7px;right:7px;bottom:6px;height:5px;border:1px solid var(--accent)}nav{display:flex;gap:28px}nav a{font-size:.9375rem;text-decoration:none;color:var(--muted);padding:10px 0}nav a[aria-current=page]{color:var(--accent);box-shadow:0 2px var(--accent)}.eyebrow{font-size:.875rem;letter-spacing:.15em;color:var(--accent);font-weight:750}.hero{display:grid;grid-template-columns:1.08fr 1fr;gap:58px;align-items:center;padding:64px 0 58px}.hero .lead{max-width:35rem;color:var(--muted);font-size:1.06rem}.button{display:inline-flex;align-items:center;justify-content:space-between;gap:28px;padding:13px 22px;min-height:50px;background:var(--ink);color:#fff;text-decoration:none;font-weight:700;border:1px solid var(--ink)}.button:hover{background:var(--blue)}.text-link{font-weight:700}.hero .small{margin-top:16px}.diagram{background:var(--panel);padding:30px;border-top:4px solid var(--accent);position:relative}.diagram svg{width:100%;height:auto;display:block;max-height:260px}.diagram figcaption{font-size:.9375rem;text-align:center}.diagram figure{margin:0}.diagram .equation{display:flex;justify-content:space-between;gap:12px;padding-top:20px;border-top:1px solid #c8d7dc;font-variant-numeric:tabular-nums}.equation strong{display:block;font-size:1.6rem;line-height:1.4;color:var(--ink)}.equation span{font-size:.875rem;color:var(--muted)}.equation .sign{font-size:1.4rem;align-self:center}.section{padding:45px 0;border-top:1px solid var(--line)}.section-title{display:flex;align-items:baseline;justify-content:space-between;gap:25px}.cards{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:22px}.card{border:1px solid var(--line);padding:28px;display:flex;flex-direction:column}.card .number{font-size:.875rem;color:var(--accent);letter-spacing:.1em;font-weight:700}.card h3{font-size:1.35rem}.card p{color:var(--muted)}.card .card-link{margin-top:auto;font-weight:700}.card .measure{font-size:2.8rem;color:var(--ink);line-height:1.4;font-weight:750;font-variant-numeric:tabular-nums;margin-bottom:16px}.card .measure span{font-size:1rem;font-weight:500;margin-left:6px}.guide-feature{background:var(--panel);padding:38px;display:grid;grid-template-columns:1fr 1.25fr;gap:40px;margin-bottom:50px}.guide-feature p{color:var(--muted)}.guide-feature h2{max-width:22rem}.method{max-width:830px;padding-bottom:50px}.method p{color:var(--muted)}.crumb{font-size:.875rem;color:var(--muted);padding-top:28px}.crumb a{color:var(--muted)}.article-header{max-width:850px;padding:30px 0 25px}.article-header h1{font-size:clamp(1.9rem,3.7vw,2.9rem)}.article-header .lead{font-size:1.05rem;color:var(--muted)}.article-header .small{margin-bottom:0}.article-nav{border-block:1px solid var(--line);padding:10px 0;flex-wrap:wrap;gap:10px 28px}.article-nav a{font-size:.9rem}.article-section{padding-top:44px;scroll-margin-top:20px}.article-section>p{max-width:860px}.callout{border-left:4px solid var(--accent);background:#fff6ee;padding:20px 25px;margin:25px 0}.callout p:last-child{margin-bottom:0}.table-scroll{overflow-x:auto;border:1px solid var(--line);scrollbar-gutter:stable}table{border-collapse:collapse;width:100%;min-width:720px;font-size:.9375rem}caption{text-align:left;padding:18px;font-weight:700}th,td{text-align:left;padding:18px;vertical-align:top;border-bottom:1px solid var(--line);border-right:1px solid var(--line)}thead th{background:var(--ink);color:#fff;font-weight:650}tbody th{background:var(--panel);min-width:160px}td strong{font-size:1.2rem}tr:last-child>*{border-bottom:0}tr>*:last-child{border-right:0}.table-note{font-size:.875rem;color:var(--muted);margin-top:12px}.calculator{background:var(--panel);padding:30px;margin:22px 0}.calculator h3{margin-bottom:12px}.input-row{display:grid;grid-template-columns:1fr 1fr;gap:24px;margin:20px 0}label{display:block;font-weight:650;font-size:.9375rem}input,select{font:inherit;color:var(--ink);width:100%;min-height:50px;border:1px solid #95abb4;background:#fff;border-radius:0;padding:9px 13px;margin-top:7px}select{font-size:.9375rem}.unit-input{display:flex;align-items:center;gap:14px}.unit-input input{min-width:0}.field-help{font-size:.875rem;color:var(--muted);margin:8px 0 0;font-weight:400}.procedure{margin:0 0 22px;padding-left:1.4rem;color:var(--muted);font-size:.9375rem}.procedure li+li{margin-top:5px}.result{margin-top:24px;border-top:1px solid #bbcdd3;padding-top:24px}.result-lead{font-weight:700;margin-bottom:14px}.result-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.result-grid>div{background:#fff;border-top:3px solid var(--blue);padding:20px}.result-grid p{font-size:.875rem;margin-bottom:7px}.result-grid strong{display:block;font-size:1.8rem;line-height:1.5}.result-grid span{font-size:.875rem;display:block;color:var(--muted)}.result>.small{margin-top:16px;margin-bottom:0}.steps{list-style:none;padding:0;counter-reset:step;max-width:870px}.steps li{counter-increment:step;position:relative;padding:0 0 28px 58px}.steps li:before{content:counter(step,decimal-leading-zero);position:absolute;left:0;top:0;color:var(--accent);font-size:1.1rem;font-weight:700}.steps h3{margin-bottom:10px}.steps p{color:var(--muted)}.example{display:grid;grid-template-columns:1fr 1fr;gap:24px;margin:25px 0}.example>div{border-top:3px solid var(--accent);background:var(--panel);padding:26px}.example .total{font-size:1.7rem;font-weight:700;line-height:1.5}.source-list{padding-left:1.25rem;font-size:.9375rem}.source-list li{margin-bottom:12px}.source-list span{font-size:.875rem;display:block;color:var(--muted)}.article-end{padding-bottom:58px}.related{border:1px solid var(--line);padding:28px;margin-top:40px}.related p{margin:8px 0 0;color:var(--muted)}.footer{background:var(--ink);color:#d4e0e3;padding:35px 0}.footer .wrap{display:flex;justify-content:space-between;gap:38px;align-items:flex-start}.footer .brand{color:#fff}.footer p{font-size:.875rem;margin-bottom:8px;max-width:660px}.footer a{color:#fff}.footer .small{color:#d4e0e3}details{margin-top:20px;border-block:1px solid var(--line);padding:15px 0}summary{cursor:pointer;font-weight:700}details p{margin:18px 0 8px}.formula{font-size:1.15rem;font-weight:700;line-height:1.8;font-variant-numeric:tabular-nums}.noscript{background:#fff6ee;border:1px solid var(--accent);padding:20px}
@media(max-width:860px){.hero{gap:28px;grid-template-columns:1fr 1fr;padding:42px 0}.hero h1{font-size:2.55rem}.diagram{padding:20px}.cards{gap:15px}.card{padding:21px}.card .measure{font-size:2.2rem}.guide-feature{gap:24px;padding:28px}.footer .wrap{display:block}.footer .brand{margin-bottom:20px}.input-row{gap:18px}.result-grid>div{padding:16px}.result-grid strong{font-size:1.5rem}}
@media(max-width:620px){.wrap{width:calc(100% - 36px)}.masthead .wrap{display:block;padding:20px 0 10px}.brand{font-size:1.4rem}.masthead nav{gap:24px;margin-top:12px}.masthead nav a{font-size:.875rem}.hero{display:block;padding:32px 0}.hero h1{font-size:2.5rem}.diagram{margin-top:32px}.diagram svg{max-height:210px}.cards{grid-template-columns:1fr}.card{padding:24px}.card .measure{font-size:2.5rem}.guide-feature{grid-template-columns:1fr;gap:10px;padding:24px}.section-title{display:block}.section-title .small{margin-bottom:18px}.section{padding:32px 0}.article-header{padding-top:24px}.article-nav{gap:0 20px}.article-section{padding-top:32px}.calculator{padding:20px}.input-row{grid-template-columns:1fr;gap:18px}.result-grid{grid-template-columns:1fr}.result-grid>div{display:grid;grid-template-columns:1fr 1fr;column-gap:14px;align-items:center}.result-grid p{margin:0}.result-grid span{grid-column:2}.result-grid strong{font-size:1.6rem}.example{grid-template-columns:1fr}.callout{padding:18px}.steps li{padding-left:44px}h2{font-size:1.5rem}.source-list{overflow-wrap:anywhere}.footer{padding:28px 0}.related{padding:22px}}