/* ── Subpage layout ── */
.page {
  padding-top: var(--header-h);
}

.page-hero {
  padding-block: clamp(5rem, 14vh, 8rem);
  border-bottom: 1px solid var(--color-border);
}

.page-hero--dark {
  background: var(--color-bg-dark);
  color: var(--color-text-on-dark);
  border-bottom-color: var(--color-border-dark);
}

.page-hero--dark .type-kicker,
.page-hero--dark .type-lead {
  color: var(--color-text-on-dark-muted);
}

.page-hero--dark .type-display {
  color: var(--color-text-on-dark);
}

.page-section {
  padding-block: var(--section-y);
}

.page-section--lg {
  padding-block: var(--section-y-lg);
}

.page-section--warm {
  background: var(--color-bg-warm);
}

.page-section--dark {
  background: var(--color-bg-dark);
  color: var(--color-text-on-dark);
}

.page-section--dark .type-lead,
.page-section--dark .type-body,
.page-section--dark .card__body {
  color: var(--color-text-on-dark-muted);
}

.page-section--dark .card {
  background: var(--color-bg-dark-elevated);
  border-color: var(--color-border-dark);
}

.page-section--dark .card__title {
  color: var(--color-text-on-dark);
}

.page-section__head {
  max-width: var(--max-width-prose);
  margin-bottom: clamp(2.5rem, 6vw, 4rem);
}

.page-section__head .type-display {
  margin-top: var(--space-4);
}

.page-flow {
  max-width: var(--max-width-prose);
}

.page-flow p + p {
  margin-top: 1.5rem;
}

.page-flow .type-body + .type-body {
  margin-top: 1.5rem;
}

/* ── Principles page — same language as TOP chapters ── */
.page--principles .page-hero--dark {
  padding-block: clamp(6rem, 17vh, 10rem);
}

/* Section rhythm — varied scroll tempo */
.page--principles .why-chapter {
  min-height: min(105svh, 960px);
  display: flex;
  align-items: center;
  padding-block: clamp(8rem, 20vh, 12rem);
}

.page--principles .why-chapter .container {
  width: 100%;
}

.page--principles .why-chapter .chapter__index {
  margin-bottom: clamp(2.5rem, 5vw, 3.5rem);
}

.page--principles .why-chapter .prose {
  margin-top: clamp(2.25rem, 5vw, 3.25rem);
}

.page--principles .why-chapter .prose p + p {
  margin-top: clamp(1.75rem, 4vw, 2.25rem);
}

.page--principles .why-chapter__bridge {
  margin-top: clamp(4.5rem, 11vw, 7rem);
  padding-top: clamp(3.25rem, 8vw, 5rem);
  border-top: 1px solid var(--color-border);
}

.page--principles .why-chapter__bridge .statement {
  max-width: 15em;
  line-height: var(--leading-snug);
}

.page--principles .why-chapter__bridge-body {
  margin-top: clamp(1.5rem, 3vw, 2rem);
  max-width: 26em;
}

/* Principle chapters — typography & spacing */
.page--principles .principle-chapter {
  display: flex;
  align-items: center;
  padding-block: clamp(6rem, 14vh, 9rem);
}

.page--principles .principle-chapter--rhythm-a {
  min-height: 100svh;
}

.page--principles .principle-chapter--rhythm-b {
  min-height: 90svh;
  align-items: flex-start;
  padding-top: clamp(7rem, 16vh, 10rem);
}

.page--principles .principle-chapter--rhythm-c {
  min-height: 94svh;
}

.page--principles .principle-chapter .container {
  width: 100%;
}

.page--principles .principle-chapter .chapter__index {
  margin-bottom: clamp(2.75rem, 5.5vw, 3.75rem);
}

.page--principles .principle-chapter__article {
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: var(--tracking-wider);
  color: var(--color-text-muted);
  margin-bottom: 0.625rem;
}

.page--principles .principle-chapter .chapter__title {
  line-height: 1.06;
  max-width: 14ch;
}

.page--principles .principle-chapter .statement {
  max-width: 13em;
  line-height: 1.12;
  letter-spacing: var(--tracking-tight);
}

.page--principles .principle-chapter .prose {
  margin-top: clamp(2.75rem, 5.5vw, 3.75rem);
  max-width: 31em;
  font-size: 1.0625rem;
  line-height: 1.88;
  color: var(--color-text-secondary);
}

/* Why Seven */
.page--principles .reason-chapter {
  min-height: min(92svh, 820px);
  display: flex;
  align-items: center;
  padding-block: clamp(8rem, 18vh, 11rem);
}

.page--principles .reason-chapter .container {
  width: 100%;
}

.page--principles .reason-chapter .chapter__title {
  max-width: 14ch;
}

.page--principles .reason-chapter__prose {
  margin-top: clamp(2.5rem, 6vw, 3.75rem);
}

.page--principles .reason-chapter__prose p {
  font-size: clamp(1.0625rem, 2vw, 1.1875rem);
  line-height: 1.95;
  letter-spacing: 0.01em;
}

.page--principles .reason-chapter__prose p + p {
  margin-top: clamp(2.25rem, 5vw, 3rem);
}

/* まとめ — closing resonance */
.page--principles .summary-chapter {
  min-height: min(88svh, 760px);
  display: flex;
  align-items: center;
  padding-block: clamp(8rem, 20vh, 12rem);
}

.page--principles .summary-chapter .container {
  width: 100%;
}

.page--principles .summary-chapter__prose {
  margin-top: clamp(2.5rem, 6vw, 3.75rem);
}

.page--principles .summary-chapter__prose p:first-child {
  font-family: var(--font-display);
  font-size: clamp(1.375rem, 2.8vw, 1.75rem);
  font-weight: 500;
  line-height: 1.45;
  letter-spacing: var(--tracking-tight);
  color: var(--color-text);
  max-width: 20em;
}

.page--principles .summary-chapter__prose p + p {
  margin-top: clamp(2rem, 4.5vw, 2.75rem);
  max-width: 34em;
}

/* Next — quiet handoff to MEASURE OS */
.page--principles .page-closing--principles {
  min-height: min(62svh, 560px);
  display: flex;
  align-items: center;
  padding-block: clamp(7rem, 18vh, 10rem);
  border-top: none;
}

.page--principles .page-closing--principles .container {
  width: 100%;
}

.page--principles .page-next--principles {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.page--principles .page-next--principles .page-next__label {
  margin-bottom: clamp(1.25rem, 3vw, 1.75rem);
  color: var(--color-text-on-dark-muted);
  letter-spacing: 0.16em;
}

.page--principles .chapter .chapter__title + .prose,
.page--principles .chapter .chapter__title + .statement {
  margin-top: clamp(2rem, 5vw, 3rem);
}

.page--principles .principle-chapter .chapter__title + .statement {
  margin-top: clamp(2.75rem, 5.5vw, 3.75rem);
}

/* Measure OS: implementation flow */
.impl-block {
  display: grid;
  gap: clamp(2.5rem, 6vw, 4rem);
  align-items: center;
}

@media (min-width: 900px) {
  .impl-block {
    grid-template-columns: 1fr 1.05fr;
    gap: 3.5rem;
  }

  .impl-block--reverse {
    direction: rtl;
  }

  .impl-block--reverse > * {
    direction: ltr;
  }
}

.impl-block__copy {
  max-width: 28em;
}

.impl-block__label {
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: var(--space-4);
}

.impl-block__title {
  font-size: var(--text-2xl);
  font-weight: 600;
  letter-spacing: var(--tracking-tight);
  line-height: var(--leading-snug);
  margin-bottom: var(--space-4);
}

.impl-block__body {
  font-size: var(--text-base);
  line-height: var(--leading-relaxed);
  color: var(--color-text-secondary);
}

.impl-block__body p + p {
  margin-top: 1.25rem;
}

/* OSTRA: pillar sequence */
.pillar-sequence {
  display: flex;
  flex-direction: column;
  gap: clamp(3rem, 8vw, 5rem);
}

.pillar-step {
  max-width: 36em;
}

.pillar-step__en {
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: var(--space-3);
}

.pillar-step__title {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  font-weight: 600;
  letter-spacing: var(--tracking-tight);
  line-height: var(--leading-tight);
  margin-bottom: var(--space-4);
}

.pillar-step__body {
  font-size: var(--text-lg);
  line-height: var(--leading-relaxed);
  color: var(--color-text-secondary);
}

.page-closing {
  padding-block: var(--section-y-lg);
  border-top: 1px solid var(--color-border);
}

.page-closing--dark {
  background: var(--color-bg-dark);
  color: var(--color-text-on-dark-muted);
  border-top-color: var(--color-border-dark);
}

.page-closing__text {
  font-size: var(--text-lg);
  line-height: var(--leading-relaxed);
  max-width: 32em;
}

.page-closing__text p + p {
  margin-top: 1.5rem;
}

.page-next {
  margin-top: var(--space-12);
  padding-top: var(--space-8);
  border-top: 1px solid var(--color-border);
}

.page-next--dark {
  border-top-color: var(--color-border-dark);
}

.page-next__label {
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: var(--space-4);
}

.page-next--dark .page-next__label,
.page-section--dark .page-next__label {
  color: var(--color-text-on-dark-muted);
}

.page-next__link {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  font-family: var(--font-display);
  font-size: clamp(1.125rem, 2.2vw, 1.375rem);
  font-weight: 500;
  letter-spacing: var(--tracking-tight);
  line-height: 1.35;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding-bottom: 0.3rem;
  position: relative;
  transition: color var(--duration-fast) var(--ease-out);
}

.page-next__link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 1px;
  background: currentColor;
  opacity: 0.28;
  transform: scaleX(0.42);
  transform-origin: left center;
  transition:
    opacity var(--duration-fast) var(--ease-out),
    transform 280ms var(--ease-out);
}

.page-next__link:hover {
  color: var(--color-text);
}

.page-next__link:hover::after {
  opacity: 0.72;
  transform: scaleX(1);
}

.page-next--dark .page-next__link {
  color: var(--color-text-on-dark-muted);
}

.page-next--dark .page-next__link::after {
  opacity: 0.32;
}

.page-next--dark .page-next__link:hover {
  color: var(--color-text-on-dark);
}

.page-next--dark .page-next__link:hover::after {
  opacity: 0.78;
}

.page-next__arrow {
  display: inline-block;
  font-size: 0.88em;
  line-height: 1;
  opacity: 0.55;
  transition:
    transform var(--duration-fast) var(--ease-out),
    opacity var(--duration-fast) var(--ease-out);
}

.page-next__link:hover .page-next__arrow {
  transform: translateX(3px);
  opacity: 0.9;
}

@media (prefers-reduced-motion: reduce) {
  .page-next__link::after {
    transform: scaleX(1);
    transition: opacity var(--duration-fast);
  }

  .page-next__arrow {
    transition: opacity var(--duration-fast);
  }

  .page-next__link:hover .page-next__arrow {
    transform: none;
  }
}

/* Experience gallery — 実画面 */
.experience-gallery {
  display: grid;
  gap: var(--space-6);
  margin-top: clamp(2.5rem, 6vw, 4rem);
}

@media (min-width: 900px) {
  .experience-gallery {
    grid-template-columns: repeat(3, 1fr);
  }
}

.experience-gallery__cap {
  padding: var(--space-3) var(--space-4) var(--space-4);
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--color-text-muted);
  text-align: center;
}