:root{--paper:#f8f9fb;--surface:#fff;--ink:#20384b;--muted:#546574;--line:#d5dfe4;--accent:#006b67;--mint:#cef3e8;--space:8px;--radius:16px}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:32px}body{margin:0;background:var(--paper);color:var(--ink);font-family:"Hiragino Kaku Gothic ProN","Yu Gothic",Meiryo,sans-serif;font-size:16px;line-height:1.85;-webkit-font-smoothing:antialiased}a{color:var(--accent);text-underline-offset:5px}a:hover{text-decoration-thickness:2px}a:focus-visible,summary:focus-visible{outline:3px solid var(--accent);outline-offset:6px;border-radius:4px}img{max-width:100%;height:auto;display:block}p,h1,h2,h3{margin:0}p+p{margin-top:16px}h1,h2,h3{font-feature-settings:"palt";text-wrap:balance}h1{font-size:clamp(40px,5.5vw,72px);line-height:1.28;letter-spacing:-.055em;font-weight:800}h2{font-size:clamp(28px,3.5vw,44px);line-height:1.4;letter-spacing:-.04em}h3{font-size:20px;line-height:1.5}small,.small{font-size:13px;line-height:1.8;color:var(--muted)}.wrap{width:min(1120px,calc(100% - 64px));margin:auto}.skip{position:absolute;top:-100px}.skip:focus{top:12px;background:var(--surface);z-index:3;padding:16px}.nav{display:flex;align-items:center;justify-content:space-between;gap:24px;padding-block:24px}.brand{display:flex;align-items:center;gap:12px;color:var(--ink);font-weight:800;text-decoration:none;white-space:nowrap}.brand img{width:36px;height:36px;border-radius:8px}.navlinks{display:flex;gap:24px;font-size:14px}.navlinks a{color:var(--muted);text-decoration:none}.navlinks a:hover{color:var(--accent)}.hero{display:grid;grid-template-columns:1.2fr 1fr;align-items:center;gap:64px;padding-block:64px 96px}.hero-copy{max-width:600px}.scope{font-size:14px;letter-spacing:.08em;margin-bottom:24px;color:var(--accent);font-weight:700}.hero p.lead{margin-block:32px;color:var(--muted);max-width:480px;font-size:18px}.accent{color:var(--accent)}.actions{display:flex;align-items:center;gap:24px;flex-wrap:wrap}.button{display:inline-flex;min-height:48px;padding:12px 24px;align-items:center;justify-content:center;background:var(--accent);color:white;text-decoration:none;border-radius:8px;font-weight:700}.button:hover{background:#005450;text-decoration:none}.secondary{font-size:14px}.hero small{display:block;margin-top:16px}.device-stage{position:relative;isolation:isolate;display:flex;justify-content:center;padding:24px 32px}.device-stage:before{content:"";position:absolute;inset:12% 0 8%;background:var(--mint);border-radius:var(--radius);z-index:-1}.hero .device{width:300px;transform:rotate(3deg)}.section{padding-block:96px;border-top:1px solid var(--line)}.section-head{max-width:700px;margin-bottom:48px}.section-head p{margin-top:24px;color:var(--muted);max-width:620px}.lesson{display:grid;grid-template-columns:1fr 1fr;gap:64px;align-items:center}.worked{background:var(--surface);border:1px solid var(--line);padding:32px;border-radius:var(--radius)}.worked p{font-size:15px}.formula{font-family:"Avenir Next",Arial,sans-serif;font-size:clamp(32px,4vw,48px);line-height:1.4;letter-spacing:-.03em;color:var(--accent);margin:32px 0}.worked .answer{display:flex;gap:16px;align-items:center;margin-bottom:16px}.check{display:grid;place-items:center;background:var(--mint);color:var(--accent);width:32px;height:32px;border-radius:50%;font-weight:800}.feature-list{display:grid;gap:32px}.feature-list p{color:var(--muted);margin-top:8px}.diagram-layout{display:grid;grid-template-columns:1fr 1fr;gap:96px;align-items:center}.diagram-layout .device{width:280px;margin:auto}.diagram-layout h2{margin-bottom:24px}.diagram-layout p{color:var(--muted)}.topics{display:grid;grid-template-columns:repeat(2,1fr);gap:0 48px;margin:32px 0 0;padding:0;list-style:none}.topics li{padding:16px 0;border-bottom:1px solid var(--line);font-size:14px}.pricing{display:grid;grid-template-columns:1fr 1fr;gap:48px}.plan{padding:32px;border:1px solid var(--line);border-radius:var(--radius);background:var(--surface)}.plan.featured{border:2px solid var(--accent)}.plan h3{font-size:24px}.price{font-family:"Avenir Next",Arial,sans-serif;font-size:40px;font-weight:700;margin:16px 0;line-height:1.4}.price span{font-family:inherit;font-size:14px;color:var(--muted);font-weight:500;margin-left:8px}.plan ul{padding-left:24px;margin:24px 0 0}.plan li{padding-block:4px;font-size:15px}.plan .small{margin-top:24px}.section .footnote{max-width:800px;margin-top:32px}.faq{max-width:840px}.faq details{border-bottom:1px solid var(--line);padding:24px 0}.faq summary{cursor:pointer;font-weight:700;min-height:44px;display:flex;align-items:center;justify-content:space-between;gap:24px;list-style:none}.faq summary::-webkit-details-marker{display:none}.faq summary:after{content:"＋";font-weight:400;color:var(--accent)}.faq details[open] summary:after{content:"−"}.faq details p{white-space:pre-line;margin-top:16px;color:var(--muted);font-size:15px}.faq .refs{font-size:13px;margin-top:16px}.faq .refs a{display:block;margin-top:8px}.linkrow{margin-top:32px}.contact{display:grid;grid-template-columns:1.2fr 1fr;gap:48px}.contact p{color:var(--muted);margin-top:24px}.contact-address{font-family:"Avenir Next",Arial,sans-serif;font-size:clamp(24px,3vw,32px);font-weight:600;align-self:center}.footer{padding-block:32px;border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:24px;flex-wrap:wrap}.footer nav{display:flex;gap:24px;font-size:13px}.footer a{color:var(--muted)}.document{max-width:800px;padding-block:64px 96px}.document h1{font-size:40px}.document h2{font-size:24px;margin-top:48px;margin-bottom:16px}.document .intro{margin:24px 0 48px;color:var(--muted)}.document p{white-space:pre-line}.document .faq{margin-top:32px}.status{display:inline-block;background:var(--mint);color:var(--accent);border-radius:4px;padding:4px 8px;font-size:12px;margin-bottom:24px}.bottom-note{margin-top:32px}.legal-list{padding-left:24px}.legal-list li{margin-block:8px}
@media(max-width:760px){.wrap{width:calc(100% - 40px)}.nav{gap:16px;padding-block:16px}.navlinks{gap:16px;font-size:12px}.navlinks a:first-child{display:none}.hero{grid-template-columns:1fr;gap:32px;padding-block:48px 64px}.hero p.lead{font-size:16px;margin-block:24px}.device-stage{padding:24px}.hero .device{width:240px}.section{padding-block:64px}.section-head{margin-bottom:32px}.lesson,.diagram-layout,.pricing,.contact{grid-template-columns:1fr;gap:32px}.worked,.plan{padding:24px}.diagram-layout .device{width:240px}.topics{gap:0 24px}.topics li{font-size:13px}.footer{padding-block:24px}.document{padding-block:48px 64px}.document h1{font-size:32px}.contact-address{font-size:28px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}