/* ============================================================
   Stream Blog — 共有スタイル（blog.html / blog-article.html）
   index.html のデザイントークンを踏襲
   ============================================================ */
:root{
  --blue:#2563eb;--mid:#3b82f6;--aqua:#06b6d4;--light:#eff6ff;
  --ink:#0d1f4e;--sub:#64748b;--gold:#f59e0b;--green:#10b981;
  --white:#ffffff;--bg-soft:#f6f9ff;--line:#e2e8f0;--nav-dark:#111827;
  --grad:linear-gradient(90deg,#2563eb,#3b82f6,#06b6d4);
  --grad-v:linear-gradient(160deg,#2563eb,#06b6d4);
  --grad-135:linear-gradient(135deg,#2563eb 0%,#3b82f6 50%,#06b6d4 100%);
  --radius:16px;
  --shadow:0 10px 40px rgba(13,31,78,.10);
  --shadow-lg:0 24px 70px rgba(13,31,78,.16);
  --maxw:1140px;
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{font-family:"Noto Sans JP","Inter",system-ui,sans-serif;color:var(--ink);background:var(--white);line-height:1.85;-webkit-font-smoothing:antialiased;overflow-x:hidden}
a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}
.container{max-width:var(--maxw);margin:0 auto;padding:0 24px}
.eyebrow{display:inline-flex;align-items:center;gap:12px;font-family:"Inter",sans-serif;font-weight:700;font-size:13px;letter-spacing:.16em;text-transform:uppercase;color:var(--blue);margin-bottom:16px}
.eyebrow::before{content:"";width:26px;height:3px;background:var(--grad);border-radius:2px}
.center{text-align:center}
.center .eyebrow{justify-content:center}
.section-title{font-size:clamp(27px,4vw,42px);font-weight:900;line-height:1.35;letter-spacing:.01em;margin-bottom:18px}
.section-title .g{background:var(--grad);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent}
.section-lead{color:var(--sub);font-size:16px;max-width:660px}
.center .section-lead{margin:0 auto}
.btn{display:inline-flex;align-items:center;gap:8px;font-weight:700;font-size:15px;padding:15px 32px;border-radius:999px;transition:.25s;cursor:pointer;border:none;white-space:nowrap}
.btn-primary{background:var(--grad-v);color:#fff;box-shadow:0 8px 26px rgba(37,99,235,.34)}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 14px 34px rgba(37,99,235,.46)}
.btn-ghost{background:#fff;color:var(--ink);border:1px solid var(--line)}
.btn-ghost:hover{border-color:var(--blue);color:var(--blue);transform:translateY(-2px)}
.btn-white{background:#fff;color:var(--blue)}
.btn-white:hover{transform:translateY(-2px);box-shadow:var(--shadow-lg)}

/* ===== Header ===== */
header{position:fixed;top:0;left:0;right:0;z-index:100;background:rgba(255,255,255,.82);backdrop-filter:blur(14px);border-bottom:1px solid transparent;transition:.3s}
header.scrolled{border-bottom-color:var(--line);box-shadow:0 4px 20px rgba(13,31,78,.05)}
.nav{display:flex;align-items:center;justify-content:space-between;height:74px}
.logo{display:flex;align-items:center;gap:10px;font-family:"Inter",sans-serif;font-weight:800;font-size:22px;letter-spacing:.02em;color:var(--ink)}
.logo svg{width:34px;height:34px;flex-shrink:0}
.nav-links{display:flex;align-items:center;gap:28px}
.nav-links a{font-size:14.5px;font-weight:500;color:var(--sub);transition:.2s}
.nav-links a:hover{color:var(--blue)}
.nav-links a.active{color:var(--blue);font-weight:700}
.nav-cta{padding:11px 22px;font-size:14px;color:#fff!important}
.menu-btn{display:none;background:none;border:none;cursor:pointer;flex-direction:column;gap:5px}
.menu-btn span{width:24px;height:2px;background:var(--ink);transition:.3s;border-radius:2px}

/* ===== Blog thumbnails (gradient fallback, index.htmlと共通) ===== */
.blog-thumb{aspect-ratio:16/9;position:relative;overflow:hidden;display:flex;align-items:center;justify-content:center;background:var(--grad-135)}
.blog-thumb.g1{background:var(--grad-135)}
.blog-thumb.g2{background:linear-gradient(135deg,#0d1f4e,#2563eb)}
.blog-thumb.g3{background:linear-gradient(135deg,#06b6d4,#3b82f6)}
.blog-thumb .grid-lines{position:absolute;inset:0;background-image:linear-gradient(rgba(255,255,255,.08) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.08) 1px,transparent 1px);background-size:32px 32px}
.blog-thumb .thumb-tag{position:relative;z-index:2;color:rgba(255,255,255,.95);font-family:"Inter",sans-serif;font-weight:800;font-size:20px;letter-spacing:.06em;text-transform:uppercase;padding:0 18px;text-align:center}
.blog-thumb img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}

/* ===== Blog card ===== */
.blog-card{display:flex;flex-direction:column;background:#fff;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;transition:.3s;height:100%}
.blog-card:hover{transform:translateY(-6px);box-shadow:var(--shadow-lg);border-color:transparent}
.blog-body{padding:22px 24px 24px;display:flex;flex-direction:column;flex:1}
.blog-meta{display:flex;align-items:center;gap:12px;margin-bottom:10px}
.blog-cat{font-size:12px;font-weight:700;color:var(--blue);letter-spacing:.04em;background:var(--light);padding:4px 11px;border-radius:999px}
.blog-date{font-size:12.5px;color:var(--sub);font-family:"Inter",sans-serif;font-weight:600;letter-spacing:.02em}
.blog-ttl{font-size:17px;font-weight:800;line-height:1.55;margin-bottom:10px;color:var(--ink);display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden}
.blog-desc{font-size:13.5px;color:var(--sub);line-height:1.8;display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden;margin-bottom:16px}
.blog-more{margin-top:auto;font-size:13px;font-weight:700;color:var(--blue)}

/* ===== Blog list page ===== */
.blog-hero{padding:132px 0 10px;position:relative;overflow:hidden}
.blog-hero::before{content:"";position:absolute;top:-30%;right:-10%;width:56vw;height:56vw;background:radial-gradient(circle,rgba(37,99,235,.12),transparent 62%);z-index:-1}
.blog-filters{display:flex;flex-wrap:wrap;gap:10px;justify-content:center;margin:34px 0 8px}
.filter-chip{font-size:13.5px;font-weight:700;color:var(--sub);background:#fff;border:1px solid var(--line);padding:9px 20px;border-radius:999px;cursor:pointer;transition:.2s}
.filter-chip:hover{border-color:var(--blue);color:var(--blue)}
.filter-chip.active{background:var(--grad-v);color:#fff;border-color:transparent}
.blog-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:26px;margin-top:36px}
.blog-empty{text-align:center;color:var(--sub);padding:60px 0;font-size:15px}

/* ===== Article page ===== */
.article-wrap{max-width:820px;margin:0 auto;padding:120px 24px 0}
.article-back{display:inline-flex;align-items:center;gap:7px;font-size:13.5px;font-weight:700;color:var(--sub);margin-bottom:24px;transition:.2s}
.article-back:hover{color:var(--blue)}
.article-head .blog-meta{margin-bottom:16px}
.article-title{font-size:clamp(26px,4.2vw,40px);font-weight:900;line-height:1.42;letter-spacing:.01em;margin-bottom:18px}
.article-cover{border-radius:20px;overflow:hidden;margin:14px 0 40px;box-shadow:var(--shadow);aspect-ratio:16/8}
.article-cover .blog-thumb{aspect-ratio:16/8}
.article-cover .thumb-tag{font-size:26px}

/* 記事本文タイポグラフィ */
.article-body{font-size:16px;line-height:2;color:#1f2b4d}
.article-body>*+*{margin-top:20px}
.article-body .lead{font-size:17.5px;line-height:2;color:var(--ink);font-weight:500;padding:20px 24px;background:var(--bg-soft);border-left:4px solid var(--blue);border-radius:0 12px 12px 0}
.article-body h2{font-size:24px;font-weight:900;line-height:1.5;margin-top:52px;padding-bottom:14px;border-bottom:2px solid var(--line);position:relative}
.article-body h2::after{content:"";position:absolute;left:0;bottom:-2px;width:64px;height:2px;background:var(--grad)}
.article-body h3{font-size:19px;font-weight:800;line-height:1.6;margin-top:36px;color:var(--ink)}
.article-body p{color:#334065}
.article-body strong{font-weight:800;color:var(--ink);background:linear-gradient(transparent 62%,rgba(6,182,212,.20) 62%)}
.article-body a{color:var(--blue);font-weight:700;text-decoration:underline;text-underline-offset:3px}
.article-body ul,.article-body ol{padding-left:4px;margin-left:4px}
.article-body li{list-style:none;position:relative;padding-left:30px;margin-top:12px;color:#334065}
.article-body ul li::before{content:"";position:absolute;left:6px;top:14px;width:8px;height:8px;border-radius:50%;background:var(--grad-v)}
.article-body ol{counter-reset:oli}
.article-body ol li{counter-increment:oli}
.article-body ol li::before{content:counter(oli);position:absolute;left:0;top:2px;width:22px;height:22px;border-radius:7px;background:var(--grad-v);color:#fff;font-family:"Inter",sans-serif;font-weight:800;font-size:12px;display:flex;align-items:center;justify-content:center}
.article-body blockquote{margin:28px 0;padding:24px 28px;background:var(--ink);color:#e7eeff;border-radius:16px;font-size:16px;line-height:1.9;font-weight:500;position:relative;box-shadow:var(--shadow)}
.article-body blockquote::before{content:"“";position:absolute;top:2px;left:16px;font-size:60px;color:rgba(124,198,255,.4);font-family:Georgia,serif;line-height:1}
.article-body img{border-radius:14px;margin:24px 0;box-shadow:var(--shadow)}
.article-body code{background:var(--light);color:var(--blue);font-size:.9em;padding:2px 8px;border-radius:6px;font-family:ui-monospace,SFMono-Regular,Menlo,monospace}

/* 記事フッター CTA */
.article-cta{margin:64px 0 0;background:var(--grad-135);color:#fff;border-radius:24px;padding:52px 40px;text-align:center;position:relative;overflow:hidden}
.article-cta::before{content:"";position:absolute;inset:0;background-image:linear-gradient(rgba(255,255,255,.06) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.06) 1px,transparent 1px);background-size:44px 44px;opacity:.6}
.article-cta .inner{position:relative;z-index:1}
.article-cta h3{font-size:clamp(22px,3vw,30px);font-weight:900;line-height:1.5;margin-bottom:14px}
.article-cta p{color:rgba(255,255,255,.9);margin-bottom:26px;font-size:15px}

/* 関連記事 */
.related{margin-top:80px;padding-top:8px}
.related h3{font-size:20px;font-weight:900;margin-bottom:26px;text-align:center}
.related .blog-grid{margin-top:0}

/* ===== Footer（index.htmlと共通） ===== */
footer{background:#0a1428;color:#8a97ac;padding:64px 0 34px;font-size:14px;margin-top:96px}
.foot-top{display:flex;justify-content:space-between;flex-wrap:wrap;gap:40px;padding-bottom:40px;border-bottom:1px solid rgba(255,255,255,.08)}
.foot-brand{max-width:340px}
.foot-brand .logo{color:#fff;margin-bottom:16px}
.foot-brand .logo svg{width:32px;height:32px}
.foot-brand p{font-size:13.5px;line-height:1.9;color:#8a97ac}
.foot-cols{display:flex;gap:60px;flex-wrap:wrap}
.foot-col h5{color:#fff;font-size:13px;letter-spacing:.06em;margin-bottom:16px;font-weight:700}
.foot-col a{display:block;margin-bottom:11px;color:#8a97ac;transition:.2s;font-size:13.5px}
.foot-col a:hover{color:#fff}
.foot-bottom{padding-top:24px;text-align:center;font-size:12.5px;color:#5a6884}

/* ===== reveal ===== */
.js .reveal{opacity:0;transform:translateY(28px);transition:.7s cubic-bezier(.2,.7,.2,1)}
.js .reveal.in{opacity:1;transform:none}
@media(prefers-reduced-motion:reduce){.js .reveal{opacity:1;transform:none;transition:none}}

/* ===== Responsive ===== */
@media(max-width:900px){
  .nav-links{position:fixed;top:74px;left:0;right:0;background:#fff;flex-direction:column;align-items:stretch;padding:20px 24px;gap:6px;border-bottom:1px solid var(--line);transform:translateY(-140%);transition:.35s;box-shadow:var(--shadow)}
  .nav-links.open{transform:none}
  .nav-links a{padding:12px 4px;font-size:16px}
  .nav-cta{text-align:center;justify-content:center;margin-top:8px}
  .menu-btn{display:flex}
  .blog-grid{grid-template-columns:repeat(2,1fr);gap:20px}
}
@media(max-width:640px){
  .blog-grid{grid-template-columns:1fr}
  .blog-hero{padding:112px 0 4px}
  .article-wrap{padding-top:104px}
  .article-body blockquote{padding:22px 22px 22px 24px}
  .article-cta{padding:40px 24px}
}