:root{
  --navy:#1c3f72;--navy-d:#16335d;--navy-dd:#122b4f;--blue:#2f6fc4;--blue-l:#5b93dc;
  --ink:#1f2a3a;--muted:#69727f;--line:#e6eaf0;--line-soft:#eef2f7;--surface:#f5f8fc;--surface-2:#eef4fb;
  --serif:"Noto Serif JP",serif;
  --sans:"Noto Sans JP",-apple-system,BlinkMacSystemFont,sans-serif;
  --maxw:1080px;--readw:760px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:var(--sans);color:var(--ink);background:#fff;line-height:1.95;font-size:15px;-webkit-font-smoothing:antialiased}
a{color:var(--blue);text-decoration:none}
img{max-width:100%;display:block}

.site-head{position:sticky;top:0;z-index:30;background:rgba(255,255,255,.92);backdrop-filter:blur(10px);border-bottom:1px solid var(--line-soft)}
.head-inner{max-width:var(--maxw);margin:0 auto;padding:0 32px;height:68px;display:flex;align-items:center;justify-content:space-between}
.logo{display:inline-flex;align-items:center;gap:11px}
.logo-mark{width:32px;height:32px;border-radius:9px;background:var(--navy);display:flex;align-items:center;justify-content:center;color:#fff}
.logo-mark svg{width:18px;height:18px}
.logo-wm{font-family:var(--serif);font-size:19px;font-weight:600;letter-spacing:.1em;color:var(--navy)}
.back{font-size:13px;color:var(--muted);display:inline-flex;align-items:center;gap:6px}
.back:hover{color:var(--blue)}

main{max-width:var(--maxw);margin:0 auto;padding:0 32px}

/* index hero */
.blog-head{text-align:center;padding:56px 0 44px;border-bottom:1px solid var(--line)}
.blog-head .eyebrow{font-size:11px;letter-spacing:.18em;color:var(--blue);font-weight:500;margin-bottom:14px}
.blog-head h1{font-family:var(--serif);font-size:32px;font-weight:600;letter-spacing:.05em;color:var(--navy)}
.blog-head p{font-size:14px;color:var(--muted);margin-top:14px}

/* card list */
.post-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:26px;padding:48px 0 20px}
.post-card{display:block;color:inherit;border:1px solid var(--line);border-radius:14px;overflow:hidden;transition:transform .25s,box-shadow .25s;background:#fff}
.post-card:hover{transform:translateY(-4px);box-shadow:0 18px 38px rgba(28,63,114,.12)}
.post-thumb{aspect-ratio:16/9;display:flex;align-items:center;justify-content:center;color:#fff}
.post-thumb.t1{background:linear-gradient(135deg,#16335d,#3a6cb0)}
.post-thumb.t2{background:linear-gradient(135deg,#2f6fc4,#7bb0e6)}
.post-thumb svg{width:54px;height:54px;opacity:.92}
.post-thumb img{width:100%;height:100%;object-fit:cover;display:block}
.post-body{padding:22px 22px 24px}
.post-tag{display:inline-block;font-size:11px;letter-spacing:.04em;color:var(--blue);background:var(--surface-2);padding:4px 11px;border-radius:6px;margin-bottom:12px}
.post-body h2{font-family:var(--serif);font-size:18px;font-weight:600;line-height:1.55;color:var(--ink);margin-bottom:10px}
.post-body p{font-size:13px;color:var(--muted);line-height:1.85;margin-bottom:14px}
.post-meta{font-size:12px;color:#9aa3af}
.post-card .more{font-size:13px;color:var(--blue);font-weight:500;margin-top:12px;display:inline-block}

/* article */
.article{max-width:var(--readw);margin:0 auto}
.article-head{padding:50px 0 30px;border-bottom:1px solid var(--line)}
.article-head .tag{display:inline-block;font-size:11px;letter-spacing:.05em;color:var(--blue);background:var(--surface-2);padding:5px 13px;border-radius:6px;margin-bottom:18px}
.article-head h1{font-family:var(--serif);font-size:31px;font-weight:600;line-height:1.5;letter-spacing:.02em;color:var(--navy);margin-bottom:18px}
.article-head .meta{font-size:12.5px;color:var(--muted)}
.article-hero{aspect-ratio:16/8;border-radius:14px;margin:30px 0 8px;display:flex;align-items:center;justify-content:center;color:#fff;overflow:hidden}
.article-hero img{width:100%;height:100%;object-fit:cover;display:block}
.article-hero.t1{background:linear-gradient(135deg,#16335d,#3a6cb0)}
.article-hero.t2{background:linear-gradient(135deg,#2f6fc4,#7bb0e6)}
.article-hero svg{width:74px;height:74px;opacity:.92}

.article-body{padding:34px 0 10px}
.article-body .lead{font-size:16px;color:#2a3650;line-height:2.05;margin-bottom:30px}
.article-body h2{font-family:var(--serif);font-size:22px;font-weight:600;color:var(--navy);margin:42px 0 16px;padding-bottom:10px;border-bottom:2px solid var(--surface-2)}
.article-body h3{font-family:var(--serif);font-size:17px;font-weight:600;color:var(--ink);margin:30px 0 12px}
.article-body p{font-size:15px;color:#33405a;line-height:2.05;margin-bottom:18px}
.article-body ul,.article-body ol{margin:0 0 20px 1.3em}
.article-body li{font-size:15px;color:#33405a;line-height:1.95;margin-bottom:8px}
.article-body strong{font-weight:700;color:var(--navy)}
.callout{background:var(--surface);border:1px solid var(--line-soft);border-left:3px solid var(--blue);border-radius:0 10px 10px 0;padding:18px 22px;margin:24px 0}
.callout p{margin:0;font-size:14px;color:#33405a}
.toc-box{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:20px 24px;margin:8px 0 10px}
.toc-box .t{font-size:12px;color:var(--muted);margin-bottom:10px}
.toc-box ol{margin:0 0 0 1.2em}
.toc-box li{font-size:13.5px;margin-bottom:6px}
.toc-box a{color:var(--ink)}
.toc-box a:hover{color:var(--blue)}

.cta-band{background:linear-gradient(120deg,var(--navy-d),var(--navy));color:#fff;border-radius:16px;padding:34px 36px;margin:46px 0 10px;text-align:center}
.cta-band h3{font-family:var(--serif);font-size:21px;font-weight:600;color:#fff;margin-bottom:10px}
.cta-band p{font-size:13.5px;color:rgba(255,255,255,.85);margin-bottom:20px}
.cta-band a{display:inline-flex;align-items:center;gap:8px;background:#fff;color:var(--navy);font-size:14px;font-weight:500;padding:12px 24px;border-radius:8px}

.article-nav{max-width:var(--readw);margin:30px auto 0;padding:26px 0;border-top:1px solid var(--line);display:flex;justify-content:space-between;font-size:13.5px}
.article-nav a{display:inline-flex;align-items:center;gap:7px}

.site-foot{background:var(--navy-dd);color:rgba(255,255,255,.7);padding:46px 32px 28px;margin-top:60px;text-align:center}
.site-foot .logo{justify-content:center;margin-bottom:12px}
.site-foot .logo-wm{color:#fff}
.site-foot .logo-mark{background:rgba(255,255,255,.12)}
.site-foot .lk{display:flex;gap:18px;justify-content:center;flex-wrap:wrap;margin:14px 0 4px}
.site-foot .lk a{font-size:12.5px;color:rgba(255,255,255,.75)}
.site-foot .copy{font-size:11.5px;color:rgba(255,255,255,.4);margin-top:22px}

@media(max-width:560px){
  .head-inner,main{padding-left:20px;padding-right:20px}
  .blog-head h1,.article-head h1{font-size:24px}
  .article-body h2{font-size:19px}
  .article-nav{flex-direction:column;gap:12px}
}