/* ===================================================================
   About page: modern sans-serif system aligned with the article
   design language (square 4px, AA contrast, no serif, no italics).
   =================================================================== */

#about-main { background: var(--color-bg); }

.about-book {
  max-width: var(--max-width);
  margin: auto;
  padding: 64px 24px 0;
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 64px;
}

/* ---------- Sticky chapter index rail ---------- */
.about-index { position: sticky; top: 120px; align-self: start; }

.about-kicker {
  font-size: 0.95rem;
  font-weight: 750;
  letter-spacing: -0.01em;
  color: var(--color-primary);
}

.about-index-title {
  font-size: 25px;
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.02em;
  color: var(--color-text);
  margin: 14px 0 26px;
}

.about-index nav { display: grid; gap: 5px; }

.about-index nav a {
  display: flex;
  align-items: baseline;
  gap: 12px;
  font-size: 15px;
  font-weight: 550;
  padding: 10px 0;
  color: var(--color-text-muted);
}

.about-index nav a span {
  font-size: 13px;
  color: var(--color-text-light);
}

.about-index nav a:hover {
  color: var(--color-text);
  text-decoration: underline;
  text-underline-offset: 5px;
}

.about-index-note {
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-text-light);
  margin-top: 35px;
}

/* ---------- Opening ---------- */
.about-pages { min-width: 0; }

.about-opening {
  padding-bottom: 48px;
  border-bottom: 1px solid var(--color-border);
}

.about-opening h1 {
  font-family: var(--font-display);
  font-size: clamp(38px, 4vw, 50px);
  font-weight: 600;
  line-height: 1.12;
  letter-spacing: -0.02em;
  color: var(--color-text);
  margin: 0 0 22px;
  text-wrap: balance;
}

.about-opening-lead {
  font-size: 23px;
  font-weight: 650;
  line-height: 1.5;
  letter-spacing: -0.015em;
  font-style: normal;
  color: var(--color-primary);
  margin-bottom: 28px;
  max-width: 30em;
}

.about-opening-copy,
.about-prose {
  font-size: 19px;
  line-height: 1.85;
  max-width: 40em;
  color: var(--color-text);
}

.about-opening-copy p,
.about-prose p { margin-bottom: 18px; }

.about-photo { margin: 32px 0 0; }

.about-photo img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 10px;
}

.about-photo figcaption {
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-text-light);
  padding-top: 12px;
}

/* ---------- Chapters ---------- */
.about-chapter {
  padding: 52px 0;
  border-bottom: 1px solid var(--color-border);
}

.about-chapter.about-ending {
  border-bottom: 0;
  padding-bottom: 56px;
}

.about-pages section { scroll-margin-top: 110px; }

.about-split { display: block; }

.about-pages h2 {
  font-family: var(--font-display);
  font-size: 30px;
  line-height: 1.22;
  font-weight: 600;
  margin: 0 0 24px;
  letter-spacing: -0.015em;
  text-wrap: balance;
}

.about-prose p:last-child { margin-bottom: 0; }

.about-statement {
  background: var(--color-secondary-bg);
  border-left: 5px solid var(--color-primary);
  border-radius: 0 12px 12px 0;
  padding: 25px 30px;
  margin-top: 30px;
}

.about-statement p {
  font-size: 24px;
  font-weight: 700;
  line-height: 1.45;
  letter-spacing: -0.02em;
  color: var(--color-primary);
  margin: 0;
  text-wrap: balance;
}

/* ---------- Principles ---------- */
.about-principles > div {
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  gap: 25px;
  padding: 22px 0;
  border-top: 1px solid var(--color-border-light);
}

.about-principles > div:first-child { border: 0; padding-top: 4px; }
.about-principles > div:last-child { padding-bottom: 0; }

.about-principles dt {
  font-size: 16px;
  font-weight: 700;
  line-height: 1.7;
  color: var(--color-text);
}

.about-principles dd {
  font-size: 17px;
  line-height: 1.85;
  color: var(--color-text-muted);
}

.about-values-heading {
  font-size: 18px;
  font-weight: 800;
  line-height: 1.4;
  letter-spacing: -0.015em;
  margin: 32px 0 22px;
}

.about-prose h3 {
  font-size: 18px;
  font-weight: 750;
  line-height: 1.5;
  letter-spacing: -0.01em;
  margin: 28px 0 10px;
}

.about-prose h3:first-child { margin-top: 0; }

/* ---------- Policy row & sign-off ---------- */
.about-policy-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  margin-top: 32px;
  font-size: 14px;
  color: var(--color-text-light);
}

.about-policy-row p { flex-basis: 100%; margin: 0; }

.about-policy-row a {
  color: var(--color-primary);
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 4px;
}

.about-conclusion-box {
  margin-top: 48px;
  padding-top: 36px;
  border-top: 1px solid var(--color-border);
}

.about-signature {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 0 0 16px;
}

.about-signature p {
  margin: 0;
  font-size: 19px;
  font-weight: 700;
  line-height: 1.5;
  letter-spacing: -0.01em;
}

.about-signature p span {
  display: block;
  font-size: 14px;
  font-weight: 500;
  line-height: 1.7;
  color: var(--color-text-light);
}

.about-conclusion-p {
  font-size: 17px;
  line-height: 1.8;
  color: var(--color-text-muted);
  max-width: 640px;
  margin-bottom: 24px;
}

.about-conclusion-actions {
  display: flex;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}

.btn-about-explore {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  font-size: 0.94rem;
  font-weight: 700;
  border-radius: var(--radius-btn);
  text-decoration: none;
}

.about-community-link {
  color: var(--color-primary);
  font-weight: 650;
  font-size: 0.95rem;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition);
}

.about-community-link:hover {
  color: var(--color-primary-hover);
  text-decoration: underline;
  text-underline-offset: 4px;
}

#about-main a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: 6px;
}

/* ---------- Responsive ---------- */
@media (max-width: 1000px) {
  .about-book {
    grid-template-columns: 180px minmax(0, 1fr);
    gap: 36px;
  }

  .about-principles > div {
    grid-template-columns: 1fr;
    gap: 9px;
  }
}

@media (max-width: 768px) {
  .about-book {
    display: block;
    padding: 30px 20px 0;
  }

  .about-index {
    position: static;
    margin-bottom: 34px;
  }

  .about-index-title,
  .about-index-note { display: none; }

  .about-index nav {
    grid-template-columns: 1fr 1fr;
    gap: 0 18px;
    margin-top: 12px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--color-border);
  }

  .about-index nav a {
    font-size: 14px;
    gap: 8px;
    padding: 8px 0;
  }

  .about-opening h1 { font-size: 40px; }

  .about-opening-lead { font-size: 21px; }

  .about-photo img { height: auto; }

  .about-pages h2 { font-size: 26px; }

  .about-chapter { padding: 36px 0; }

  .about-chapter.about-ending { padding-bottom: 40px; }

  .about-statement { padding: 22px; }

  .about-statement p { font-size: 21px; }

  .about-statement br { display: none; }
}

@media (max-width: 480px) {
  .about-opening h1 { font-size: clamp(28px, 8.7vw, 34px); }
  .about-conclusion-p { text-wrap: balance; }
}