:root {
    /* DESIGN.md 和色トークン */
    --primary: #162b4d;            /* 勝色 */
    --primary-foreground: #faf6ec;
    --primary-hover: #1f3a66;
    --accent: #3a8fa8;             /* 浅葱 */
    --accent-hover: #2a6e85;
    --accent-soft: rgba(58, 143, 168, 0.15);
    --ink: #1d1d1f;                /* 墨色 (= near-black) */
    --bg: #faf6ec;                 /* 象牙色 (page) */
    --bg-alt: #f3ede0;             /* 白茶 (section alt) */
    --ink-on-dark: #f5f3ee;
    --body-light: rgba(0, 0, 0, 0.8);
    --body-dark: rgba(255, 255, 255, 0.92);
    --border-light: rgba(0, 0, 0, 0.08);
    --border-dark: rgba(255, 255, 255, 0.12);
    --card-shadow: rgba(0, 0, 0, 0.08) 2px 4px 12px 0px;
    --font-stack: "Inter", "Noto Sans JP", "Hiragino Sans", "Hiragino Kaku Gothic ProN", Meiryo, "Helvetica Neue", Helvetica, Arial, sans-serif;
  }

  * { box-sizing: border-box; }

  html {
    -webkit-text-size-adjust: 100%;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
  }

  body {
    margin: 0;
    font-family: var(--font-stack);
    font-size: 17px;
    line-height: 1.47;
    letter-spacing: -0.357px; /* DESIGN.md §3.5 */
    color: var(--body-light);
    background: var(--bg);
  }

  a { color: inherit; text-decoration: none; }

  /* ---------- Navigation ---------- */
  /* DESIGN.md §6: backdrop-blur 不使用。不透明背景 + 下罫線 */
  .nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 48px;
    background: var(--bg);
    border-bottom: 1px solid var(--border-light);
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    color: var(--ink);
  }
  .nav-brand {
    font-size: 17px;
    font-weight: 600;
    letter-spacing: -0.374px;
  }
  .nav-links {
    display: flex;
    gap: 24px;
    font-size: 12px;
    font-weight: 400;
  }
  .nav-links a {
    opacity: 0.88;
    transition: opacity 0.2s;
  }
  .nav-links a:hover { opacity: 1; }

  /* ---------- Sections ---------- */
  .section {
    padding: 96px 24px;
    text-align: center;
  }
  /* DESIGN.md §2: ヒーロー / CTA セクションは勝色背景 + 象牙色テキスト */
  .section-dark { background: var(--primary); color: var(--ink-on-dark); }
  .section-light { background: var(--bg-alt); color: var(--ink); }
  .section-inner {
    max-width: 980px;
    margin: 0 auto;
  }

  /* ---------- Typography ---------- */
  .eyebrow {
    font-size: 17px;
    font-weight: 600;
    line-height: 1.24;
    letter-spacing: -0.374px;
    opacity: 0.7;
    margin: 0 0 12px;
  }
  .headline {
    font-size: 56px;
    font-weight: 600;
    line-height: 1.07;
    letter-spacing: -0.28px;
    margin: 0;
  }
  .section-heading {
    font-size: 40px;
    font-weight: 600;
    line-height: 1.10;
    letter-spacing: -0.2px;
    margin: 0 0 16px;
  }
  .subtitle {
    font-size: 21px;
    font-weight: 400;
    line-height: 1.38;
    letter-spacing: 0.011em;
    margin: 20px auto 0;
    max-width: 720px;
    opacity: 0.88;
  }
  .body-lead {
    font-size: 17px;
    line-height: 1.47;
    margin: 16px auto 0;
    max-width: 680px;
  }

  /* ---------- Hero ---------- */
  .hero {
    padding-top: 144px;
    padding-bottom: 112px;
  }
  .hero .cta-row { margin-top: 36px; }

  /* ---------- Buttons ---------- */
  /* DESIGN.md §4: Primary CTA / Outline は 10px 矩形角丸。ピル型 (100px) はナビ CTA とタグのみ。 */
  .cta-row {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    justify-content: center;
  }
  .btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 44px;
    padding: 0 22px;
    font-family: inherit;
    font-size: 15px;
    font-weight: 600;
    letter-spacing: -0.224px;
    border-radius: 10px;
    border: 1px solid transparent;
    cursor: pointer;
    transition: background 0.2s, color 0.2s, border-color 0.2s, opacity 0.2s;
  }
  .btn:focus-visible {
    outline: 3px solid var(--accent-soft);
    outline-offset: 2px;
  }
  /* Light セクション (= 白茶背景) のメインボタン: 勝色 bg + 象牙色 text */
  .btn-primary {
    background: var(--primary);
    color: var(--primary-foreground);
  }
  .btn-primary:hover { background: var(--primary-hover); }
  /* Dark セクション (= 勝色背景) のアウトライン: 透明 + 象牙色ボーダー / 反転ホバー */
  .btn-outline-dark {
    background: transparent;
    color: var(--ink-on-dark);
    border-color: rgba(255, 255, 255, 0.6);
  }
  .btn-outline-dark:hover { background: var(--primary-foreground); color: var(--primary); border-color: var(--primary-foreground); }
  /* Light セクション (= 白茶背景) のアウトライン: 透明 + 浅葱ボーダー */
  .btn-outline-light {
    background: transparent;
    color: var(--accent);
    border-color: var(--accent);
  }
  .btn-outline-light:hover { background: var(--accent); color: var(--primary-foreground); }
  /* Dark セクション内の Disabled CTA */
  .btn-disabled {
    background: transparent;
    color: rgba(255, 255, 255, 0.48);
    border-color: rgba(255, 255, 255, 0.24);
    cursor: not-allowed;
  }

  .inline-link {
    color: var(--accent);
    font-size: 14px;
    letter-spacing: -0.224px;
  }
  .inline-link:hover { color: var(--accent-hover); text-decoration: underline; }
  /* Dark セクション内のリンクは色を反転 (浅葱の明るめ寄り) */
  .section-dark .inline-link { color: #7fb6c8; }
  .section-dark .inline-link:hover { color: var(--primary-foreground); }

  /* ---------- Feature grid ---------- */
  .feature-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
    margin-top: 56px;
    text-align: left;
  }
  /* DESIGN.md §4: カード = 象牙色背景 + 1px ボーダー + 14px radius */
  .feature-card {
    background: var(--bg);
    border: 1px solid var(--border-light);
    border-radius: 14px;
    padding: 36px 32px;
  }
  .feature-card:hover { box-shadow: var(--card-shadow); }
  /* DESIGN.md §4 Feature Icon: 浅葱透背景 + 浅葱フォアグラウンド */
  .feature-icon {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 10px;
    background: var(--accent-soft);
    color: var(--accent);
    margin-bottom: 18px;
  }
  .feature-card h3 {
    font-size: 21px;
    font-weight: 600;
    line-height: 1.19;
    letter-spacing: 0.011em;
    margin: 0 0 10px;
    color: var(--ink);
  }
  .feature-card p {
    font-size: 14px;
    line-height: 1.43;
    letter-spacing: -0.224px;
    margin: 0;
    color: var(--body-light);
  }

  /* ---------- Highlights list (dark) ---------- */
  .highlight-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin-top: 56px;
    text-align: left;
  }
  .highlight-item {
    border-top: 1px solid var(--border-dark);
    padding-top: 18px;
  }
  .highlight-item h4 {
    font-size: 17px;
    font-weight: 600;
    line-height: 1.24;
    letter-spacing: -0.374px;
    margin: 0 0 8px;
  }
  .highlight-item p {
    font-size: 14px;
    line-height: 1.43;
    letter-spacing: -0.224px;
    margin: 0;
    opacity: 0.78;
  }

  /* ---------- Doc row ---------- */
  .doc-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
    margin-top: 48px;
    text-align: left;
  }
  .doc-card {
    background: var(--bg);
    border: 1px solid var(--border-light);
    border-radius: 14px;
    padding: 40px;
    display: flex;
    flex-direction: column;
  }
  .doc-card:hover { box-shadow: var(--card-shadow); }
  .doc-card .eyebrow {
    font-size: 14px;
    letter-spacing: -0.224px;
    color: var(--accent);
    opacity: 1;
  }
  .doc-card h3 {
    font-size: 28px;
    font-weight: 600;
    line-height: 1.14;
    letter-spacing: 0.007em;
    margin: 8px 0 12px;
    color: var(--ink);
  }
  .doc-card p {
    font-size: 14px;
    line-height: 1.43;
    letter-spacing: -0.224px;
    margin: 0 0 20px;
    color: var(--body-light);
  }
  .doc-card .cta-row { justify-content: flex-start; margin-top: auto; }

  /* ---------- Download ---------- */
  .download .platforms {
    max-width: 520px;
    margin: 48px auto 0;
    text-align: left;
  }
  .platform-card {
    border: 1px solid var(--border-dark);
    border-radius: 18px;
    padding: 28px 28px 32px;
  }
  .platform-card h4 {
    font-size: 21px;
    font-weight: 600;
    margin: 0 0 6px;
    letter-spacing: 0.011em;
  }
  .platform-card p {
    font-size: 14px;
    letter-spacing: -0.224px;
    opacity: 0.78;
    margin: 0 0 18px;
    line-height: 1.43;
  }
  .platform-meta {
    margin: 16px 0 0 !important;
    opacity: 1 !important;
  }
  .platform-meta a {
    color: #7fb6c8;
    text-decoration: none;
  }
  .platform-meta a:hover {
    text-decoration: underline;
  }
  /* DESIGN.md §4 Eyebrow / Tag: ピル型 (100px radius) */
  .pill {
    display: inline-block;
    font-size: 12px;
    font-weight: 600;
    letter-spacing: -0.12px;
    padding: 4px 10px;
    border-radius: 100px;
    background: rgba(255, 255, 255, 0.12);
    color: var(--ink-on-dark);
    margin-left: 8px;
    vertical-align: 2px;
  }

  /* ---------- Footer ---------- */
  footer {
    background: var(--bg);
    color: var(--body-light);
    border-top: 1px solid var(--border-light);
    padding: 40px 24px 32px;
    font-size: 12px;
    letter-spacing: -0.12px;
    line-height: 1.33;
  }
  footer .footer-inner {
    max-width: 980px;
    margin: 0 auto;
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    justify-content: space-between;
  }
  footer .footer-legal {
    max-width: 980px;
    margin: 20px auto 0;
    padding-top: 16px;
    border-top: 1px solid var(--border-light);
    display: flex;
    flex-wrap: wrap;
    gap: 18px;
    justify-content: center;
    color: rgba(0, 0, 0, 0.48);
  }
  footer .footer-legal a { color: rgba(0, 0, 0, 0.48); }
  footer a { color: var(--accent); }
  footer a:hover { color: var(--accent-hover); text-decoration: underline; }

  /* ---------- Responsive ---------- */
  @media (max-width: 860px) {
    .section { padding: 72px 20px; }
    .hero { padding-top: 120px; padding-bottom: 80px; }
    .headline { font-size: 40px; letter-spacing: -0.2px; }
    .section-heading { font-size: 30px; }
    .subtitle { font-size: 18px; }
    .feature-grid,
    .highlight-grid,
    .doc-row {
      grid-template-columns: 1fr;
    }
    .nav-links { display: none; }
  }