:root {
  --bg: #080b11;
  --surface: #131923;
  --surface-soft: #18202f;
  --surface-ghost: rgba(26, 34, 49, 0.72);
  --ink: #f7f9ff;
  --muted: #a9b3c9;
  --muted-strong: #c7cee1;
  --line: #252e40;
  --accent: #8aa9ff;
  --accent-strong: #5f7bff;
  --accent-soft: rgba(102, 140, 255, 0.16);
  --badge: rgba(80, 110, 170, 0.2);
  --max-width: 960px;
  --measure: 68ch;
  --radius-lg: 18px;
  --radius-md: 12px;
  --radius-sm: 8px;
  --title-font: "Playfair Display", "Times New Roman", serif;
  --body-font: "Inter", "Segoe UI", "Hiragino Sans", "Noto Sans JP", sans-serif;
}

* {
  box-sizing: border-box;
}

::selection {
  background: rgba(123, 155, 255, 0.35);
}

html,
body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--body-font);
  line-height: 1.65;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--accent-strong);
  text-decoration: underline;
}

img,
svg {
  max-width: 100%;
  height: auto;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 28px;
}

main {
  padding-bottom: 96px;
}

h1,
h2,
h3,
h4 {
  font-family: var(--title-font);
  font-weight: 600;
  letter-spacing: 0.01em;
}

h1 {
  font-size: clamp(2rem, 4vw, 2.8rem);
  line-height: 1.2;
}

h2 {
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  margin-top: 0;
}

h3 {
  font-size: clamp(1.3rem, 2vw, 1.6rem);
}

p {
  max-width: var(--measure);
}

ul,
ol {
  padding-left: 1.25rem;
}

/* Cover */
.cover {
  position: relative;
  overflow: hidden;
  padding: 140px 0 110px;
  background: radial-gradient(circle at 30% 20%, rgba(120, 160, 255, 0.18), transparent 60%),
    radial-gradient(circle at 75% 30%, rgba(70, 120, 255, 0.12), transparent 65%),
    linear-gradient(160deg, #0b0f16 0%, #06070b 100%);
  border-bottom: 1px solid rgba(70, 110, 170, 0.35);
}

.cover::after {
  content: "";
  position: absolute;
  inset: 18% 8% auto 12%;
  height: 420px;
  background: radial-gradient(circle, rgba(102, 140, 255, 0.22) 0%, transparent 55%);
  filter: blur(42px);
  opacity: 0.85;
  pointer-events: none;
}

.cover__inner {
  position: relative;
  z-index: 2;
  display: flex;
  flex-direction: column;
  gap: 26px;
}

.cover__badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: 999px;
  background: var(--badge);
  color: var(--muted-strong);
  font-size: 0.85rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.cover__title {
  margin: 0;
  font-size: clamp(3rem, 8vw, 4.6rem);
  font-weight: 600;
}

.cover__subtitle {
  margin: 0;
  font-size: clamp(1.35rem, 3vw, 1.8rem);
  color: var(--muted-strong);
  max-width: var(--measure);
}

.cover__logline {
  margin: 0;
  color: var(--muted);
  max-width: var(--measure);
}

.cover__cta {
  align-self: flex-start;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 12px 22px;
  border-radius: var(--radius-md);
  border: 1px solid rgba(120, 150, 255, 0.35);
  background: rgba(30, 42, 70, 0.45);
  color: var(--ink);
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.cover__cta:hover {
  text-decoration: none;
  background: rgba(80, 110, 200, 0.45);
}

/* Introductory section */
.section {
  margin: 80px 0 0;
}

.section:first-of-type {
  margin-top: 70px;
}

.section-header {
  margin-bottom: 32px;
}

.section-header p {
  color: var(--muted);
}

/* Table of contents */
.toc {
  background: var(--surface);
  padding: 40px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--line);
  box-shadow: 0 22px 45px rgba(6, 10, 20, 0.45);
}

.toc h2 {
  margin-bottom: 16px;
}

.toc-groups {
  display: grid;
  gap: 34px;
}

.toc-group h3 {
  margin-bottom: 10px;
  color: var(--muted-strong);
  font-size: 1rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.toc-group ol,
.toc-group ul {
  list-style-position: inside;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.toc-entry {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 10px 14px;
  border-radius: var(--radius-md);
  background: transparent;
  transition: background 0.2s ease, border 0.2s ease;
  border: 1px solid transparent;
}

.toc-entry:hover {
  background: var(--accent-soft);
  border-color: rgba(120, 150, 255, 0.4);
}

.toc-entry strong {
  font-family: var(--body-font);
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: 0;
}

.toc-note {
  color: var(--muted);
  font-size: 0.92rem;
}

/* Editorial notes */
.notes {
  margin-top: 56px;
  background: var(--surface-soft);
  border-radius: var(--radius-lg);
  border: 1px solid var(--line);
  padding: 32px 36px;
}

.notes h2 {
  margin-top: 0;
}

.notes ul {
  margin: 16px 0 0;
  padding-left: 1.1rem;
  color: var(--muted);
}

/* Interior pages */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(8, 11, 17, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(38, 48, 70, 0.6);
}

.site-identity,
.site-header .container {
  display: flex;
  flex-direction: column;
  padding: 20px 0;
  gap: 6px;
}

.site-identity__back,
.site-header .site-subtitle {
  font-size: 0.9rem;
  color: var(--muted-strong);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.site-identity__series,
.site-header .site-title {
  margin: 0;
  font-family: var(--title-font);
  font-size: 1.15rem;
  color: var(--ink);
  font-weight: 600;
}

.site-header .site-tagline {
  margin: 2px 0 0;
  color: var(--muted);
  font-size: 0.95rem;
}

article {
  margin-top: 48px;
  background: var(--surface);
  padding: 42px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--line);
  box-shadow: 0 22px 45px rgba(6, 10, 20, 0.45);
}

article header h1 {
  margin: 0 0 12px;
}

.meta {
  margin: 0 0 28px;
  color: var(--muted);
  font-size: 0.9rem;
}

blockquote {
  margin: 28px 0;
  padding: 18px 24px;
  border-left: 4px solid rgba(120, 150, 255, 0.6);
  background: rgba(32, 40, 60, 0.4);
  color: var(--muted-strong);
  font-style: italic;
}

.card {
  margin: 32px 0;
  padding: 28px;
  background: var(--surface-soft);
  border-radius: var(--radius-md);
  border: 1px solid rgba(60, 78, 110, 0.65);
  box-shadow: inset 0 0 0 1px rgba(80, 110, 160, 0.08);
}

.card h2,
.card h3 {
  margin-top: 0;
}

.note-box {
  border-style: dashed;
}

.negative {
  color: var(--accent);
}

.navline {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  justify-content: space-between;
  margin-top: 46px;
}

.navline a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  border-radius: var(--radius-md);
  border: 1px solid rgba(120, 150, 255, 0.35);
  background: rgba(24, 32, 48, 0.52);
  color: var(--ink);
  font-weight: 600;
}

.navline a:hover {
  text-decoration: none;
  background: rgba(75, 100, 170, 0.5);
}

.site-footer {
  border-top: 1px solid rgba(34, 44, 64, 0.7);
  padding: 32px 0 56px;
  color: var(--muted);
  font-size: 0.85rem;
}

.site-footer .container {
  padding-top: 0;
}

@media (max-width: 720px) {
  .container {
    padding: 0 20px;
  }

  .cover {
    padding: 110px 0 80px;
  }

  .cover__inner {
    gap: 22px;
  }

  .cover__cta {
    align-self: stretch;
    justify-content: center;
  }

  .toc {
    padding: 30px 24px;
  }

  article {
    padding: 34px 24px;
  }

  .navline {
    flex-direction: column;
    align-items: stretch;
  }

  .navline a {
    justify-content: center;
  }
}

article hr,
.article-divider {
  border: none;
  border-top: 1px solid rgba(60, 80, 120, 0.4);
  margin: 42px 0;
}