/* ============================================================
   Grus Systems — main.css
   依存ゼロ。ダーク/ライトは [data-theme] で切替。
   ============================================================ */

:root {
  --max: 1080px;
  --narrow: 720px;
  --pad: clamp(1.1rem, 4vw, 2rem);
  --radius: 12px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN",
    "Hiragino Sans", Meiryo, system-ui, sans-serif;
  --font-mono: "SFMono-Regular", "JetBrains Mono", "Fira Code", ui-monospace, Menlo, monospace;
  --step: clamp(1rem, 0.92rem + 0.4vw, 1.075rem);
}

/* ---- テーマ: ダーク（既定） ---- */
[data-theme="dark"] {
  --bg: #0c0d10;
  --bg-soft: #14161b;
  --bg-card: #15171d;
  --border: #23262e;
  --border-strong: #313640;
  --fg: #e7e9ee;
  --fg-soft: #aeb4bf;
  --fg-dim: #757c89;
  --accent: #ff7a00;
  --accent-bright: #ff7a00;
  --accent-soft: #2e1d0c;
  --shadow: 0 1px 2px rgba(0,0,0,.4), 0 8px 30px rgba(0,0,0,.35);
}
/* ---- テーマ: ライト ---- */
[data-theme="light"] {
  --bg: #ffffff;
  --bg-soft: #f6f7f9;
  --bg-card: #ffffff;
  --border: #e6e8ec;
  --border-strong: #d3d7de;
  --fg: #14161b;
  --fg-soft: #4a505b;
  --fg-dim: #858b96;
  --accent: #e0680a;
  --accent-bright: #ff8a2b;
  --accent-soft: #fff1e6;
  --shadow: 0 1px 2px rgba(20,22,27,.04), 0 10px 30px rgba(20,22,27,.06);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-sans);
  font-size: var(--step);
  line-height: 1.7;
  letter-spacing: .005em;
  -webkit-font-smoothing: antialiased;
}

/* テーマ切替の瞬間だけ全要素の色を同期してクロスフェード（ホバー等には影響しない） */
@media (prefers-reduced-motion: no-preference) {
  .theme-transition,
  .theme-transition *,
  .theme-transition *::before,
  .theme-transition *::after {
    transition: background-color .28s ease, border-color .28s ease,
                color .28s ease, fill .28s ease, stroke .28s ease,
                opacity .28s ease !important;
  }
}

h1, h2, h3, h4 { line-height: 1.25; letter-spacing: -.01em; font-weight: 650; }
h1 { font-size: clamp(1.9rem, 1.4rem + 2.4vw, 3rem); }
h2 { font-size: clamp(1.4rem, 1.1rem + 1.4vw, 2rem); }
h3 { font-size: 1.2rem; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }
img { max-width: 100%; height: auto; }

.wrap { width: 100%; max-width: var(--max); margin-inline: auto; padding-inline: var(--pad); }
.narrow { max-width: var(--narrow); }
.center-block { text-align: center; }

.skip-link {
  position: absolute; left: -999px; top: 0; z-index: 100;
  background: var(--accent); color: #fff; padding: .5rem .9rem; border-radius: 0 0 8px 0;
}
.skip-link:focus { left: 0; }

/* ---- ヘッダー ---- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: saturate(1.4) blur(10px);
  border-bottom: 1px solid var(--border);
}
.header-inner { display: flex; align-items: center; gap: 1rem; min-height: 78px; transition: min-height .25s ease; }
[data-scrolled] .header-inner { min-height: 58px; }
[data-scrolled] .site-header { box-shadow: 0 6px 22px rgba(0,0,0,.06); }
.brand { display: inline-flex; align-items: center; gap: .55rem; color: var(--fg); font-weight: 650; letter-spacing: -.01em; padding: .5rem .7rem; margin: 0 0 0 -.7rem; border-radius: 10px; transition: background-color .2s ease; }
.brand:hover { text-decoration: none; background: var(--bg-soft); }
.brand-mark { display: inline-flex; align-items: center; }
.brand-mark svg { height: 26px; width: auto; display: block; }
.footer-brand .brand-mark svg { height: 22px; }

/* ヘッダーのロゴ（明/暗2枚を不透明度クロスフェードで切替＝引っかかり防止） */
.brand-logos { position: relative; display: inline-block; line-height: 0; }
.brand-logo { height: 38px; width: auto; display: block; transition: opacity .28s ease, height .25s ease; }
[data-scrolled] .brand-logo { height: 30px; }
.footer-brand .brand-logo { height: 30px; }
.brand-logo--dark { position: absolute; top: 0; left: 0; opacity: 0; }
.brand-logo--light { opacity: 1; }
[data-theme="dark"] .brand-logo--light { opacity: 0; }
[data-theme="dark"] .brand-logo--dark { opacity: 1; }

.site-nav { margin-left: auto; }
.nav-list { display: flex; gap: .25rem; list-style: none; margin: 0; padding: 0; }
.nav-list a {
  display: inline-block; padding: .45rem .7rem; border-radius: 8px;
  color: var(--fg-soft); font-size: .94rem; font-weight: 500;
}
.nav-list a:hover { color: var(--fg); background: var(--bg-soft); text-decoration: none; }
.nav-list a.active { color: var(--fg); background: var(--accent-soft); }

.header-actions { display: flex; align-items: center; gap: .4rem; }
.lang-switch { display: flex; height: 36px; gap: 2px; list-style: none; margin: 0; padding: 0; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.lang-switch li { display: flex; }
.lang-switch a { display: flex; align-items: center; padding: 0 .6rem; font-size: .78rem; font-family: var(--font-mono); color: var(--fg-dim); }
.lang-switch a:hover { background: var(--bg-soft); color: var(--fg); text-decoration: none; }

.theme-toggle, .nav-toggle {
  display: inline-grid; place-items: center; width: 36px; height: 36px;
  background: transparent; border: 1px solid var(--border); border-radius: 8px;
  color: var(--fg-soft); cursor: pointer; transition: border-color .2s, color .2s;
}
.theme-toggle:hover { color: var(--fg); border-color: var(--border-strong); }
.theme-toggle .icon-moon { display: none; }
[data-theme="dark"] .theme-toggle .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle .icon-moon { display: block; }

.nav-toggle { display: none; flex-direction: column; align-items: center; justify-content: center; gap: 4px; }
.nav-toggle span { width: 16px; height: 1.5px; background: currentColor; border-radius: 2px; transition: .2s; }

/* ---- ヒーロー ---- */
.hero { position: relative; overflow: hidden; padding: clamp(3.5rem, 8vw, 7rem) 0 clamp(2.5rem, 5vw, 4rem); border-bottom: 1px solid var(--border); }
.hero-bg { position: absolute; inset: 0; color: var(--accent); opacity: .14; pointer-events: none; }
.hero-bg .constellation { width: 100%; height: 100%; }
[data-theme="light"] .hero-bg { opacity: .12; }
.hero-inner { position: relative; }
.eyebrow {
  font-family: var(--font-mono); font-size: .8rem; letter-spacing: .14em;
  text-transform: uppercase; color: var(--accent); margin: 0 0 1rem;
}
.hero-title { margin: 0 0 1rem; max-width: 16ch; }
.hero-sub { margin: 0; max-width: 52ch; color: var(--fg-soft); font-size: clamp(1.05rem, 1rem + .4vw, 1.25rem); }
.hero-cta { display: flex; flex-wrap: wrap; gap: .7rem; margin-top: 2rem; }

.btn {
  display: inline-flex; align-items: center; gap: .4rem;
  padding: .7rem 1.25rem; border-radius: 10px;
  background: var(--accent-bright); color: #fff; font-weight: 600; font-size: .95rem;
  border: 1px solid transparent; transition: transform .12s ease, opacity .2s ease;
}
.btn:hover { text-decoration: none; opacity: .92; transform: translateY(-1px); }
.btn-ghost { background: transparent; color: var(--fg); border-color: var(--border-strong); }
.btn-ghost:hover { background: var(--bg-soft); opacity: 1; }

/* ---- セクション ---- */
.section { padding: clamp(3rem, 6vw, 5rem) 0; }
.section-title { margin: 0 0 1.8rem; font-size: clamp(1.3rem, 1.1rem + 1vw, 1.8rem); }
.lead-prose { font-size: 1.1rem; color: var(--fg-soft); }

/* ---- カード ---- */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1rem; }
.card {
  display: flex; flex-direction: column; gap: .5rem;
  padding: 1.5rem; background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); color: var(--fg); transition: border-color .2s, transform .15s, box-shadow .2s;
}
.card:hover { text-decoration: none; border-color: var(--border-strong); transform: translateY(-2px); box-shadow: var(--shadow); }
.card-tag { font-family: var(--font-mono); font-size: .72rem; letter-spacing: .1em; text-transform: uppercase; color: var(--accent); }
.card-title { margin: 0; }
.card-body { margin: 0; color: var(--fg-soft); font-size: .95rem; flex: 1; }
.card-link { margin-top: .4rem; color: var(--accent); font-size: .88rem; font-weight: 600; }

.cta-band { background: var(--bg-soft); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.cta-band h2 { margin: 0 0 .6rem; }

/* ---- 記事 / prose ---- */
.page { padding: clamp(2.5rem, 5vw, 4rem) 0 clamp(3rem, 6vw, 5rem); }
.page-head { margin-bottom: 2rem; }
.eyebrow + h1 { margin-top: .3rem; }
.lead { font-size: 1.15rem; color: var(--fg-soft); margin: .8rem 0 0; max-width: 60ch; }

.prose { max-width: 68ch; }
.prose > * + * { margin-top: 1.1rem; }
.prose h2 { margin-top: 2.6rem; padding-top: .4rem; }
.prose h3 { margin-top: 1.8rem; color: var(--fg); }
.prose p, .prose li { color: var(--fg-soft); }
.prose strong { color: var(--fg); font-weight: 650; }
.prose a { text-decoration: underline; text-underline-offset: 3px; }
.prose ul, .prose ol { padding-left: 1.3rem; }
.prose li + li { margin-top: .4rem; }
.prose code {
  font-family: var(--font-mono); font-size: .88em; padding: .12em .4em;
  background: var(--bg-soft); border: 1px solid var(--border); border-radius: 6px;
}
.prose blockquote {
  margin: 1.4rem 0; padding: .2rem 0 .2rem 1.1rem;
  border-left: 3px solid var(--accent); color: var(--fg-soft);
}
.prose hr { border: none; border-top: 1px solid var(--border); margin: 2.4rem 0; }

/* ---- Ventures ---- */
.venture-list { display: grid; gap: 1rem; margin-top: 1.5rem; }
.venture {
  padding: clamp(1.4rem, 3vw, 2.2rem); background: var(--bg-card);
  border: 1px solid var(--border); border-radius: var(--radius); scroll-margin-top: 80px;
}
.venture-head { display: flex; align-items: center; gap: .8rem; flex-wrap: wrap; }
.venture-head h2 { margin: 0; }
.badge {
  font-family: var(--font-mono); font-size: .72rem; letter-spacing: .06em;
  padding: .2rem .55rem; border-radius: 999px; color: var(--accent);
  background: var(--accent-soft); border: 1px solid var(--border);
}
.venture-tagline { margin: .6rem 0 0; color: var(--fg-dim); font-family: var(--font-mono); font-size: .85rem; }
.venture .prose { margin-top: 1rem; max-width: none; }

/* ---- フッター（ミニマル：横並び1行＋中央寄せの著作権） ---- */
.site-footer { border-top: 1px solid var(--border); background: var(--bg-soft); margin-top: 2.5rem; }
.footer-top {
  display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center;
  gap: .8rem 1.5rem; padding-block: clamp(1.6rem, 3.5vw, 2.1rem) .9rem;
}
.footer-brand { display: inline-flex; align-items: center; gap: .55rem; color: var(--fg); }
.footer-brand:hover { text-decoration: none; }
.footer-name { color: var(--fg); font-weight: 650; letter-spacing: -.01em; }
.footer-links { display: inline-flex; align-items: center; gap: 1.4rem; }
.footer-links a { color: var(--fg-soft); font-size: .9rem; }
.footer-links a:hover { color: var(--fg); }
.footer-bottom {
  display: flex; justify-content: center;
  padding-block: 0 1.6rem; color: var(--fg-dim); font-size: .8rem;
}

/* ---- レスポンシブ ---- */
@media (max-width: 760px) {
  .header-inner { min-height: 64px; gap: .5rem; position: relative; }
  [data-scrolled] .header-inner { min-height: 54px; }
  .site-header .brand-logo { height: 30px; }
  [data-scrolled] .site-header .brand-logo { height: 26px; }
  .brand { padding: .4rem .5rem; margin: 0 0 0 -.5rem; }
  .header-actions { gap: .3rem; }

  .nav-toggle { display: inline-flex; }
  .site-nav { position: static; display: flex; align-items: center; }
  .nav-list {
    position: absolute; top: 64px; left: 0; right: 0;
    flex-direction: column; gap: 0; padding: .5rem var(--pad) 1rem;
    background: var(--bg); border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow); display: none;
  }
  .nav-list.open { display: flex; }
  .nav-list a { display: block; padding: .85rem .7rem; border-radius: 8px; }
  [data-scrolled] .nav-list { top: 54px; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; scroll-behavior: auto; }
}