*,*::before,*::after{box-sizing:border-box}
:root{--bg:#f4f6f7;--paper:#fff;--ink:#182026;--muted:#59656e;--line:#d6dde1;--blue:#276b9c;--green:#277454;--red:#a64343;--yellow:#d39b28;--shadow:0 8px 24px rgba(23,37,45,.07)}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font-family:"Noto Sans JP",system-ui,-apple-system,"Segoe UI",sans-serif;line-height:1.75}
a{color:inherit}
button,a.action{font:inherit}
.shell{width:min(1160px,calc(100% - 32px));margin:auto}
.topbar{display:flex;align-items:center;justify-content:space-between;gap:20px;padding:18px 0;border-bottom:1px solid var(--line)}
.brand{font-weight:800;text-decoration:none}
.nav{display:flex;flex-wrap:wrap;gap:16px}
.nav a{color:var(--muted);font-size:13px;font-weight:700;text-decoration:none}
.hero{display:grid;grid-template-columns:minmax(0,.85fr) minmax(360px,1.15fr);gap:38px;align-items:center;padding:48px 0 40px}
.kicker{margin:0 0 8px;color:var(--blue);font-size:12px;font-weight:800;letter-spacing:.16em;text-transform:uppercase}
h1{margin:0;font-size:clamp(28px,3.4vw,42px);line-height:1.25;letter-spacing:0}
.lead{margin:16px 0 0;color:var(--muted);font-size:15px;max-width:650px}
.hero-preview{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
.hero-preview div{min-height:108px;border:1px solid var(--line);border-radius:8px;background:var(--paper);box-shadow:var(--shadow);padding:16px}
.hero-preview strong{display:block;font-size:14px}
.hero-preview span{display:block;margin-top:5px;color:var(--muted);font-size:12px}
.section{padding:36px 0;border-top:1px solid var(--line)}
.section-head{display:flex;align-items:end;justify-content:space-between;gap:24px;margin-bottom:18px}
.section-head h2{margin:0;font-size:clamp(22px,2.6vw,30px)}
.section-head p{margin:0;color:var(--muted);font-size:13px;max-width:600px}
.sample-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}
.sample-grid.three{grid-template-columns:repeat(3,minmax(0,1fr))}
.sample{align-self:start;background:var(--paper);border:1px solid var(--line);border-radius:8px;box-shadow:var(--shadow);overflow:hidden}
.sample-body{padding:18px}
.sample h2,.sample h3{margin:0 0 8px;line-height:1.4}
.sample h3{font-size:18px}
.sample p{margin:0;color:var(--muted);font-size:13px}
.sample ul{margin:12px 0 0;padding-left:20px;color:var(--muted);font-size:13px}
.actions{display:flex;flex-wrap:wrap;gap:9px;margin-top:16px}
.action{display:inline-flex;align-items:center;justify-content:center;min-height:40px;padding:8px 14px;border:1px solid var(--ink);border-radius:6px;background:var(--ink);color:#fff;font-size:13px;font-weight:800;text-decoration:none;cursor:pointer}
.action.secondary{background:#fff;color:var(--ink);border-color:var(--line)}
.palette{display:grid;grid-template-columns:repeat(5,1fr);height:110px}
.palette span{display:flex;align-items:end;padding:7px;color:#fff;font-size:10px;font-weight:800;text-shadow:0 1px 3px rgba(0,0,0,.5)}
.thumbnail{aspect-ratio:1200/630;display:flex;flex-direction:column;justify-content:end;padding:22px;color:#fff;background:#276b9c}
.thumbnail strong{font-size:clamp(20px,2.4vw,30px);line-height:1.3}
.thumbnail small{margin-top:8px;font-weight:700}
.thumb-note{background:linear-gradient(135deg,#1f5a7a,#3c8c82)}
.thumb-app{background:linear-gradient(135deg,#273247,#a34d58)}
.thumb-business{background:linear-gradient(135deg,#f3f5f7 0 64%,#276b9c 64%);color:#182026}
.envelope-wrap{display:grid;place-items:center;min-height:250px;padding:22px;background:#dfe4e7}
.envelope{position:relative;background:#fffefa;border:1px solid #c9c3b7;box-shadow:0 6px 16px rgba(0,0,0,.1)}
.envelope.naga{width:144px;height:282px}
.envelope.kaku{width:220px;height:300px}
.env-postal,.env-address,.env-name,.env-sender{position:absolute;font-size:9px;line-height:1.5;white-space:pre-line}
.vertical{writing-mode:vertical-rl}
.envelope .env-postal{top:14px;left:18px;letter-spacing:.08em}
.envelope.naga .env-address{top:54px;right:24px}
.envelope.naga .env-name{top:76px;right:64px;font-size:13px}
.envelope.naga.horizontal .env-address{top:76px;left:22px;right:auto}
.envelope.naga.horizontal .env-name{top:110px;left:22px;right:auto;font-size:13px}
.envelope.naga.horizontal .env-sender{left:22px;bottom:18px}
.envelope.kaku .env-address{top:58px;right:34px}
.envelope.kaku .env-name{top:86px;right:92px;font-size:14px}
.envelope.kaku .env-sender{left:22px;bottom:24px}
.diff{width:100%;border-collapse:collapse;font-size:12px}
.diff th,.diff td{padding:9px;border:1px solid var(--line);vertical-align:top;text-align:left}
.diff th{background:#eef2f4}
.del{background:#ffe0dc;text-decoration:line-through}
.add{background:#d8f1e2}
.note{padding:14px 16px;border-left:4px solid var(--blue);background:#edf4f8;color:#33444f;font-size:13px}
.footer{display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap;padding:28px 0 40px;border-top:1px solid var(--line);color:var(--muted);font-size:12px}
.footer div{display:flex;gap:14px;flex-wrap:wrap}
@media(max-width:820px){.hero{grid-template-columns:1fr;padding-top:34px}.sample-grid,.sample-grid.three{grid-template-columns:1fr}.section-head{align-items:start;flex-direction:column;gap:6px}}
@media(max-width:520px){.shell{width:min(100% - 22px,1160px)}.topbar{align-items:flex-start;flex-direction:column}.hero-preview{grid-template-columns:1fr}.palette{height:92px}.palette span{font-size:9px;padding:5px}.sample-body{padding:15px}.action{width:100%}}