/* =========================================================
   ネット回線の教科書 — main.css
   デザイントークン / リセット / レイアウト / ヘッダー・フッター
   コンセプト: Apple風の余白・白ベース・青アクセント・読みやすさ
   ========================================================= */

:root {
  /* --- カラー --- */
  --color-bg: #ffffff;
  --color-bg-soft: #f5f6f8;
  --color-bg-tint: #f0f5ff;
  --color-text: #1d1d1f;
  --color-text-sub: #515159;
  --color-text-mute: #86868b;
  --color-border: #e4e6eb;
  --color-accent: #0066ff;
  --color-accent-dark: #0050cc;
  --color-accent-soft: #e6f0ff;
  --color-success: #1a9e6c;
  --color-warning: #c47a00;

  /* --- カテゴリ色分け（光=青/ホームルーター=緑/モバイル=橙/格安SIM=赤） --- */
  --cat-hikari: #0066ff;
  --cat-hikari-soft: #e6f0ff;
  --cat-homerouter: #18a558;
  --cat-homerouter-soft: #e4f6ec;
  --cat-mobile: #f08400;
  --cat-mobile-soft: #fff1de;
  --cat-sim: #e0322f;
  --cat-sim-soft: #fde8e7;
  --cat-neutral: #0066ff;
  --cat-neutral-soft: #e6f0ff;

  /* --- タイポグラフィ --- */
  --font-base: -apple-system, BlinkMacSystemFont, "Hiragino Kaku Gothic ProN",
    "Hiragino Sans", "Noto Sans JP", "Yu Gothic", "Meiryo", sans-serif;
  --fs-hero: clamp(1.9rem, 5vw, 3rem);
  --fs-h1: clamp(1.6rem, 4vw, 2.25rem);
  --fs-h2: clamp(1.35rem, 3vw, 1.75rem);
  --fs-h3: 1.2rem;
  --fs-body: 1.0625rem;
  --fs-sm: 0.9375rem;
  --fs-xs: 0.8125rem;
  --lh-body: 1.85;
  --lh-tight: 1.4;

  /* --- 余白・形状 --- */
  --space-section: clamp(3rem, 8vw, 6rem);
  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 22px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04), 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
  --shadow-hover: 0 12px 36px rgba(0, 51, 153, 0.12);
  --container: 1080px;
  --container-narrow: 720px;
  --header-h: 60px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* --- リセット --- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-base);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--color-accent); text-decoration: none; transition: color 0.2s var(--ease); }
a:hover { color: var(--color-accent-dark); }
h1, h2, h3, h4 { line-height: var(--lh-tight); font-weight: 700; letter-spacing: -0.01em; }
ul, ol { padding-left: 1.25em; }
button { font-family: inherit; cursor: pointer; }

/* --- レイアウト --- */
.container { width: 100%; max-width: var(--container); margin-inline: auto; padding-inline: 20px; }
.container--narrow { max-width: var(--container-narrow); }
.section { padding-block: var(--space-section); }
.section--soft { background: var(--color-bg-soft); }
.section-head { text-align: center; margin-bottom: 2.5rem; }
.section-head h2 { font-size: var(--fs-h2); margin: 0 0 0.5rem; }
.section-head p { color: var(--color-text-sub); margin: 0; font-size: var(--fs-sm); }
.skip-link {
  position: absolute; left: -9999px; top: 0; background: var(--color-accent);
  color: #fff; padding: 10px 16px; z-index: 1000;
}
.skip-link:focus { left: 8px; top: 8px; }

/* --- ヘッダー --- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: saturate(180%) blur(18px);
  -webkit-backdrop-filter: saturate(180%) blur(18px);
  border-bottom: 1px solid var(--color-border);
}
.site-header__inner {
  display: flex; align-items: center; justify-content: space-between;
  height: var(--header-h);
}
.site-brand { display: flex; align-items: baseline; gap: 8px; }
.site-brand__name { font-size: 1.125rem; font-weight: 700; color: var(--color-text); letter-spacing: -0.02em; }
.site-brand__tag { font-size: var(--fs-xs); color: var(--color-text-mute); }
@media (max-width: 600px) { .site-brand__tag { display: none; } }

.nav-toggle {
  display: none; border: 0; background: none; width: 40px; height: 40px;
  flex-direction: column; gap: 5px; justify-content: center; align-items: center;
}
.nav-toggle span { display: block; width: 22px; height: 2px; background: var(--color-text); transition: 0.3s var(--ease); }
.main-nav ul { display: flex; gap: 24px; list-style: none; margin: 0; padding: 0; }
.main-nav a { color: var(--color-text-sub); font-size: var(--fs-sm); font-weight: 500; }
.main-nav a:hover { color: var(--color-accent); }

@media (max-width: 820px) {
  .nav-toggle { display: flex; }
  .main-nav {
    position: fixed; inset: var(--header-h) 0 auto 0;
    background: #fff; border-bottom: 1px solid var(--color-border);
    transform: translateY(-120%); transition: transform 0.35s var(--ease);
    box-shadow: var(--shadow);
  }
  .main-nav.is-open { transform: translateY(0); }
  .main-nav ul { flex-direction: column; gap: 0; padding: 8px 20px; }
  .main-nav li { border-bottom: 1px solid var(--color-border); }
  .main-nav li:last-child { border-bottom: 0; }
  .main-nav a { display: block; padding: 14px 0; }
  .nav-toggle.is-active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
  .nav-toggle.is-active span:nth-child(2) { opacity: 0; }
  .nav-toggle.is-active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
}

/* --- フッター --- */
.site-footer { background: var(--color-bg-soft); border-top: 1px solid var(--color-border); padding-block: 3rem 2rem; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 2rem; margin-bottom: 2rem; }
.footer-grid h3 { font-size: var(--fs-sm); margin: 0 0 1rem; }
.footer-grid ul { list-style: none; padding: 0; margin: 0; }
.footer-grid li { margin-bottom: 0.6rem; }
.footer-grid a { color: var(--color-text-sub); font-size: var(--fs-sm); }
.footer-brand p { color: var(--color-text-mute); font-size: var(--fs-sm); max-width: 32ch; }
.footer-bottom { border-top: 1px solid var(--color-border); padding-top: 1.5rem; text-align: center; color: var(--color-text-mute); font-size: var(--fs-xs); }
@media (max-width: 700px) { .footer-grid { grid-template-columns: 1fr 1fr; } .footer-brand { grid-column: 1 / -1; } }

/* --- パンくず --- */
.breadcrumb { padding-block: 0.9rem; font-size: var(--fs-xs); color: var(--color-text-mute); }
.breadcrumb ol { list-style: none; display: flex; flex-wrap: wrap; gap: 6px; margin: 0; padding: 0; }
.breadcrumb li:not(:last-child)::after { content: "›"; margin-left: 6px; color: var(--color-border); }

/* --- アクセシビリティ --- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.001ms !important; transition-duration: 0.001ms !important; scroll-behavior: auto !important; }
}
:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; border-radius: 4px; }