/* ===========================================================
   site-shell.css ─ サイト共通の骨格（リセット・ヘッダー・モバイルナビ）
   -----------------------------------------------------------
   2026-08-04 新設。海外コラム12本が記事HTMLに直書きしていた骨格CSSを集約。
   本文（記事の中身）のスタイルはここに書かない。
     ・記事本文の正本      : assets/css/article.css
     ・海外コラム固有の調整 : assets/css/column-global.css
   色・トークンは assets/css/tokens.css を先に読み込むこと。
   =========================================================== */

/* --- リセット --- */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Noto Sans JP", "Hiragino Kaku Gothic ProN", "Yu Gothic", Meiryo, sans-serif;
  color: var(--text);
  background: #F4F6F9;
  line-height: 1.80;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  letter-spacing: 0.02em;
}
body * { font-family: inherit; }
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }

/* --- ヘッダー（TOPページと同値：padding 10px・ロゴ38px） --- */
.site-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 40px;
  background: rgba(255,255,255,0.92);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 50;
}
.site-header .logo { display: flex; align-items: center; }
.site-header .logo img { height: 38px; width: auto; display: block; }
.site-header nav {
  display: flex;
  gap: 26px;
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--text-soft);
  font-weight: 700;
  align-items: center;
}
.site-header nav a:hover { color: var(--navy); }
.site-header nav a[aria-current="page"] { color: var(--accent); font-weight: 700; }
.site-header nav a.nav-cta {
  background: var(--navy);
  color: #fff;
  padding: 6px 16px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
}
.site-header nav a.nav-cta:hover { background: var(--accent); }

/* --- モバイルナビ（ハンバーガー） --- */
.nav-toggle { display: none; }
.hamburger { display: none; cursor: pointer; width: 36px; height: 36px; position: relative; z-index: 60; }
.hamburger span {
  position: absolute;
  left: 6px;
  width: 24px;
  height: 2px;
  background: var(--navy);
  border-radius: 8px;
  transition: transform 0.25s ease, opacity 0.2s ease, top 0.25s ease;
}
.hamburger span:nth-child(1) { top: 11px; }
.hamburger span:nth-child(2) { top: 17px; }
.hamburger span:nth-child(3) { top: 23px; }
.nav-toggle:checked ~ .hamburger span:nth-child(1) { top: 17px; transform: rotate(45deg); }
.nav-toggle:checked ~ .hamburger span:nth-child(2) { opacity: 0; }
.nav-toggle:checked ~ .hamburger span:nth-child(3) { top: 17px; transform: rotate(-45deg); }

@media (max-width: 768px) {
  .hamburger { display: block; }
  .site-header nav {
    display: flex !important;
    position: fixed;
    top: 0;
    right: -100%;
    height: 100vh;
    width: min(82vw, 320px);
    background: #fff;
    flex-direction: column;
    align-items: flex-start;
    padding: 80px 28px 32px;
    gap: 4px;
    box-shadow: -8px 0 32px rgba(11,26,51,0.18);
    transition: right 0.3s ease;
    z-index: 55;
    overflow-y: auto;
  }
  .nav-toggle:checked ~ nav { right: 0; }
  .site-header nav a { width: 100%; padding: 14px 12px; font-size: 16px; border-bottom: 1px solid #F4F6F9; }
  .site-header nav a:last-child { border-bottom: none; }
}