:root {
  --color-bg: #FFFFFF;
  --color-surface: #F7F8FA;
  --color-surface-2: #EEF1F6;
  --color-brand: #0B2545;
  --color-brand-ink: #06162B;
  --color-accent: #C9A86A;
  --color-text: #1A1A1A;
  --color-text-sub: #5A5A5A;
  --color-text-mute: #8A8F98;
  --color-border: #E5E7EB;
  --color-border-strong: #C9CED6;
  --color-danger: #8B2E2E;
  --color-success: #1F6B48;

  --radius-sm: 6px;
  --radius-md: 12px;

  --font-heading: "Shippori Mincho", "Yu Mincho", "ヒラギノ明朝 ProN", serif;
  --font-body: "Noto Sans JP", "Hiragino Sans", "ヒラギノ角ゴ ProN", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;

  --pad: clamp(20px, 4vw, 64px);
  --max: 1240px;

  --density: 1;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: var(--color-bg); color: var(--color-text); font-family: var(--font-body); font-size: 16px; line-height: 1.7; -webkit-font-smoothing: antialiased; font-feature-settings: "palt" 1; }
body[data-density="loose"] { --density: 1.25; }
body[data-density="dense"] { --density: 0.82; }

body[data-dark="true"] {
  --color-bg: #0A1628;
  --color-surface: #0F1E35;
  --color-surface-2: #152844;
  --color-brand: #E8D9B2;
  --color-brand-ink: #FAF6EC;
  --color-text: #EDE8DB;
  --color-text-sub: #9BA9BE;
  --color-text-mute: #6A7890;
  --color-border: #223556;
  --color-border-strong: #3A4E72;
}

a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; }
img { max-width: 100%; display: block; }

.mono { font-family: var(--font-mono); font-feature-settings: "tnum" 1; letter-spacing: 0.02em; }
.heading { font-family: var(--font-heading); font-weight: 600; letter-spacing: 0.02em; line-height: 1.35; color: var(--color-brand-ink); }
.eyebrow { font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.22em; text-transform: uppercase; color: var(--color-accent); font-weight: 500; }
.divider { height: 1px; background: var(--color-border); width: 100%; }
.divider-strong { height: 1px; background: var(--color-border-strong); width: 100%; }

.container { max-width: var(--max); margin: 0 auto; padding-left: var(--pad); padding-right: var(--pad); }

.section { padding: calc(96px * var(--density)) 0; border-top: 1px solid var(--color-border); }
.section-head { display: grid; grid-template-columns: 180px 1fr; gap: 40px; align-items: start; margin-bottom: 56px; }
.section-head .idx { font-family: var(--font-mono); font-size: 12px; color: var(--color-text-mute); letter-spacing: 0.12em; padding-top: 10px; border-top: 1px solid var(--color-brand); display: inline-block; min-width: 120px; }
.section-head h2 { font-family: var(--font-heading); font-size: clamp(28px, 3.4vw, 42px); font-weight: 600; margin: 0 0 12px; line-height: 1.35; color: var(--color-brand-ink); }
.section-head .lede { color: var(--color-text-sub); max-width: 62ch; font-size: 15px; }
@media (max-width: 760px) {
  .section-head { grid-template-columns: 1fr; gap: 12px; margin-bottom: 32px; }
}

.btn { display: inline-flex; align-items: center; justify-content: center; gap: 10px; height: 52px; padding: 0 24px; border-radius: var(--radius-sm); font-weight: 600; font-size: 15px; transition: 0.2s; border: 1px solid transparent; letter-spacing: 0.04em; }
.btn-primary { background: var(--color-brand); color: #fff; }
.btn-primary:hover { background: var(--color-brand-ink); transform: translateY(-1px); }
.btn-ghost { background: transparent; color: var(--color-brand-ink); border-color: var(--color-brand-ink); }
.btn-ghost:hover { background: var(--color-brand-ink); color: #fff; }
body[data-dark="true"] .btn-primary { background: var(--color-accent); color: #0A1628; }
body[data-dark="true"] .btn-ghost { color: var(--color-text); border-color: var(--color-border-strong); }

.tabular { font-variant-numeric: tabular-nums; }

/* Hairline utility */
.hairline-t { border-top: 1px solid var(--color-border); }
.hairline-b { border-bottom: 1px solid var(--color-border); }

/* Accent underline */
.accent-rule { display: inline-block; width: 40px; height: 1px; background: var(--color-accent); vertical-align: middle; }