/* ==========================================================================
   PHI OS Reality Atlas / Knowledge Journey
   ========================================================================== */

body[data-page="atlas"] {
  min-width: 320px;
  margin: 0;
  background:
    radial-gradient(circle at 8% 5%, rgba(101, 83, 166, 0.08), transparent 28rem),
    radial-gradient(circle at 92% 28%, rgba(31, 108, 115, 0.06), transparent 34rem),
    var(--paper);
  color: var(--ink);
}

body[data-page="atlas"]::selection {
  background: rgba(101, 83, 166, 0.18);
}

.atlas-shell {
  width: min(calc(100% - 3rem), var(--max));
  margin-inline: auto;
}

.atlas-header {
  position: fixed;
  min-height: 78px;
  border-bottom: 1px solid transparent;
  background: rgba(245, 243, 237, 0.78);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  transition:
    min-height 180ms ease,
    border-color 180ms ease,
    background-color 180ms ease;
}

.atlas-header.is-scrolled {
  min-height: 68px;
  border-color: var(--line);
  background: rgba(245, 243, 237, 0.94);
}

.atlas-navigation {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: clamp(0.8rem, 1.65vw, 1.55rem);
}

.atlas-navigation a {
  position: relative;
  padding: 0.45rem 0;
  color: var(--ink-soft);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-decoration: none;
  text-transform: uppercase;
  transition: color 150ms ease;
}

.atlas-navigation a::after {
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  height: 1px;
  content: "";
  background: var(--knowledge);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform 150ms ease;
}

.atlas-navigation a:hover,
.atlas-navigation a:focus-visible,
.atlas-navigation a.is-active {
  color: var(--ink);
}

.atlas-navigation a:hover::after,
.atlas-navigation a:focus-visible::after,
.atlas-navigation a.is-active::after {
  transform: scaleX(1);
}

.atlas-main {
  display: block;
  width: 100%;
}

/* ==========================================================================
   Atlas hero
   ========================================================================== */

.atlas-hero {
  position: relative;
  display: flex;
  align-items: center;
  min-height: 92svh;
  padding: 10.5rem 0 7rem;
  overflow: hidden;
  isolation: isolate;
}

.atlas-hero::before {
  position: absolute;
  inset: 0;
  z-index: -3;
  content: "";
  background:
    linear-gradient(115deg, rgba(255, 255, 255, 0.56), transparent 58%),
    linear-gradient(180deg, transparent 72%, rgba(101, 83, 166, 0.035));
}

.atlas-hero-orbit {
  position: absolute;
  top: 49%;
  right: -16vw;
  z-index: -2;
  width: min(70vw, 820px);
  aspect-ratio: 1;
  opacity: 0.42;
  transform: translateY(-50%);
  pointer-events: none;
}

.atlas-hero-orbit span {
  position: absolute;
  inset: 0;
  border: 1px solid rgba(101, 83, 166, 0.18);
  border-radius: 50%;
}

.atlas-hero-orbit span:nth-child(2) {
  inset: 18%;
  border-radius: 3px;
  transform: rotate(45deg);
}

.atlas-hero-orbit span:nth-child(3) {
  inset: 36%;
  border-color: rgba(31, 108, 115, 0.24);
}

.atlas-hero-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(270px, 0.62fr);
  align-items: end;
  gap: clamp(3rem, 8vw, 8rem);
}

.atlas-hero-copy {
  max-width: 850px;
}

.atlas-hero-copy h1 {
  max-width: 900px;
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(4.2rem, 8vw, 8.5rem);
  font-weight: 500;
  letter-spacing: -0.055em;
  line-height: 0.88;
  text-wrap: balance;
}

html[lang="zh-Hans"] .atlas-hero-copy h1 {
  max-width: 800px;
  font-size: clamp(4rem, 7.2vw, 7.4rem);
  line-height: 1.02;
}

.atlas-lead {
  max-width: 680px;
  margin: 2rem 0 0;
  color: var(--ink-soft);
  font-size: clamp(1rem, 1.3vw, 1.18rem);
  line-height: 1.7;
  text-wrap: pretty;
}

.atlas-hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-top: 2.4rem;
}

.atlas-action {
  display: inline-flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
  min-height: 49px;
  padding: 0.82rem 1.2rem;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  color: var(--ink);
  font-size: 0.82rem;
  font-weight: 600;
  text-decoration: none;
  transition:
    border-color 160ms ease,
    background-color 160ms ease,
    color 160ms ease,
    transform 160ms ease;
}

.atlas-action:hover,
.atlas-action:focus-visible {
  border-color: var(--knowledge);
  transform: translateY(-1px);
}

.atlas-action--primary {
  border-color: var(--knowledge);
  background: var(--knowledge);
  color: #fff;
  box-shadow: 0 10px 30px rgba(101, 83, 166, 0.18);
}

.atlas-action--primary:hover,
.atlas-action--primary:focus-visible {
  background: color-mix(in srgb, var(--knowledge) 90%, #000);
}

.atlas-orientation {
  width: 100%;
  padding: 1.4rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.48);
  box-shadow: 0 20px 60px rgba(25, 27, 33, 0.05);
  backdrop-filter: blur(15px);
  -webkit-backdrop-filter: blur(15px);
}

.atlas-orientation > p {
  margin: 0 0 0.35rem;
  color: var(--ink-soft);
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.atlas-orientation > strong {
  font-family: var(--serif);
  font-size: 1.75rem;
  font-weight: 500;
}

.atlas-orientation ol {
  display: grid;
  gap: 0;
  margin: 1.2rem 0 0;
  padding: 0;
  list-style: none;
}

.atlas-orientation li {
  display: grid;
  grid-template-columns: 2rem 1fr;
  align-items: center;
  gap: 0.7rem;
  min-height: 42px;
  border-top: 1px solid var(--line);
  color: var(--ink-soft);
  font-size: 0.82rem;
}

.atlas-orientation li span:first-child {
  font-size: 0.65rem;
  letter-spacing: 0.08em;
}

.atlas-orientation li.is-current {
  color: var(--knowledge);
  font-weight: 600;
}

/* ==========================================================================
   Shared Atlas sections
   ========================================================================== */

.atlas-overview,
.atlas-books,
.atlas-layers,
.knowledge-continuation,
.atlas-return {
  scroll-margin-top: 6rem;
}

.atlas-overview,
.atlas-books,
.atlas-layers,
.knowledge-continuation {
  padding: clamp(5rem, 9vw, 8rem) 0;
  border-top: 1px solid var(--line);
}

.atlas-section-heading h2 {
  max-width: 780px;
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(2.8rem, 5.2vw, 5.3rem);
  font-weight: 500;
  letter-spacing: -0.038em;
  line-height: 0.98;
  text-wrap: balance;
}

html[lang="zh-Hans"] .atlas-section-heading h2 {
  line-height: 1.12;
}

.atlas-section-heading--wide {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(260px, 0.55fr);
  align-items: end;
  gap: 3rem;
  margin-bottom: 3rem;
}

.atlas-section-heading--wide > p {
  max-width: 430px;
  margin: 0;
  color: var(--ink-soft);
  line-height: 1.7;
}

/* ==========================================================================
   Atlas overview
   ========================================================================== */

.atlas-overview-grid {
  display: grid;
  grid-template-columns: minmax(260px, 0.75fr) minmax(0, 1.25fr);
  gap: clamp(3rem, 8vw, 8rem);
}

.atlas-reading-forms {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  border-top: 1px solid var(--line-strong);
}

.atlas-reading-forms article {
  min-height: 190px;
  padding: 1.5rem 1.4rem 1.4rem 0;
  border-bottom: 1px solid var(--line);
}

.atlas-reading-forms article:nth-child(odd) {
  padding-right: 2rem;
  border-right: 1px solid var(--line);
}

.atlas-reading-forms article:nth-child(even) {
  padding-left: 2rem;
}

.atlas-reading-forms span {
  color: var(--knowledge);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
}

.atlas-reading-forms h3 {
  margin: 1.4rem 0 0.45rem;
  font-family: var(--serif);
  font-size: 1.7rem;
  font-weight: 500;
}

.atlas-reading-forms p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.9rem;
  line-height: 1.65;
}

.atlas-boundary {
  grid-column: 1 / -1;
  max-width: 890px;
  margin: 0;
  padding: 1.2rem 1.35rem;
  border-left: 3px solid var(--knowledge);
  background: rgba(101, 83, 166, 0.055);
  color: var(--ink-soft);
  line-height: 1.65;
}

/* ==========================================================================
   Three books
   ========================================================================== */

.atlas-books {
  background: rgba(255, 255, 255, 0.32);
}

.book-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.book-card {
  position: relative;
  display: flex;
  flex-direction: column;
  min-height: 490px;
  padding: 1.6rem;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: rgba(255, 255, 255, 0.58);
  box-shadow: 0 18px 50px rgba(25, 27, 33, 0.035);
}

.book-card::before {
  position: absolute;
  top: -9rem;
  right: -8rem;
  width: 18rem;
  aspect-ratio: 1;
  border: 1px solid rgba(101, 83, 166, 0.13);
  border-radius: 50%;
  content: "";
  pointer-events: none;
}

.book-card--two::before {
  border-color: rgba(31, 108, 115, 0.16);
}

.book-card--three::before {
  border-color: rgba(169, 79, 49, 0.14);
}

.book-card header {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  color: var(--ink-soft);
  font-size: 0.69rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.book-status {
  padding: 0.35rem 0.55rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  letter-spacing: 0.06em;
}

.book-status--available {
  border-color: rgba(37, 117, 94, 0.26);
  background: rgba(37, 117, 94, 0.07);
  color: var(--success);
}

.book-card h3 {
  position: relative;
  margin: 4.7rem 0 0;
  font-family: var(--serif);
  font-size: clamp(2.4rem, 3.6vw, 3.8rem);
  font-weight: 500;
  letter-spacing: -0.035em;
  line-height: 1.03;
}

html[lang="zh-Hans"] .book-card h3 {
  letter-spacing: -0.02em;
  line-height: 1.15;
}

.book-card-subtitle {
  min-height: 2.5rem;
  margin: 0.8rem 0 1.4rem;
  color: var(--knowledge);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  line-height: 1.55;
  text-transform: uppercase;
}

.book-card > p:not(.book-card-subtitle) {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.9rem;
  line-height: 1.7;
}

.book-card > a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-top: auto;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
  color: var(--ink);
  font-size: 0.8rem;
  font-weight: 600;
  text-decoration: none;
}

.book-card > a span:last-child {
  transition: transform 160ms ease;
}

.book-card > a:hover span:last-child,
.book-card > a:focus-visible span:last-child {
  transform: translateX(0.25rem);
}

/* ==========================================================================
   Fourteen-layer Atlas
   ========================================================================== */

.atlas-filter-bar {
  position: sticky;
  top: 68px;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
  padding: 0.8rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(245, 243, 237, 0.9);
  box-shadow: 0 12px 35px rgba(25, 27, 33, 0.045);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.atlas-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
}

.atlas-filters button {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  min-height: 38px;
  padding: 0.45rem 0.75rem;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: var(--ink-soft);
  font-size: 0.75rem;
  cursor: pointer;
}

.atlas-filters button small {
  opacity: 0.62;
}

.atlas-filters button:hover,
.atlas-filters button:focus-visible,
.atlas-filters button.is-active {
  background: var(--ink);
  color: #fff;
}

.atlas-filter-status {
  margin: 0 0.65rem 0 0;
  color: var(--ink-soft);
  font-size: 0.72rem;
  white-space: nowrap;
}

.atlas-node-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.8rem;
}

.atlas-node {
  scroll-margin-top: 10rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.45);
  transition:
    border-color 160ms ease,
    background-color 160ms ease,
    box-shadow 160ms ease;
}

.atlas-node:hover,
.atlas-node:focus-within,
.atlas-node[open],
.atlas-node:target {
  border-color: color-mix(in srgb, var(--knowledge) 54%, transparent);
  background: rgba(255, 255, 255, 0.78);
  box-shadow: 0 12px 38px rgba(25, 27, 33, 0.045);
}

.atlas-node summary {
  display: grid;
  grid-template-columns: 2.7rem minmax(0, 1fr) auto;
  align-items: center;
  gap: 1rem;
  min-height: 112px;
  padding: 1.25rem;
  cursor: pointer;
  list-style: none;
}

.atlas-node summary::-webkit-details-marker {
  display: none;
}

.atlas-node-index {
  color: var(--knowledge);
  font-family: var(--serif);
  font-size: 1.4rem;
}

.atlas-node-heading {
  display: grid;
  gap: 0.3rem;
}

.atlas-node-heading small {
  color: var(--ink-soft);
  font-size: 0.64rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.atlas-node-heading strong {
  font-family: var(--serif);
  font-size: 1.65rem;
  font-weight: 500;
  line-height: 1.15;
}

.atlas-node-toggle {
  display: grid;
  width: 2rem;
  height: 2rem;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  color: var(--ink-soft);
  transition: transform 180ms ease;
}

.atlas-node[open] .atlas-node-toggle {
  transform: rotate(45deg);
}

.atlas-node-content {
  padding: 0 1.25rem 1.35rem 4.95rem;
}

.atlas-node-content p {
  max-width: 540px;
  margin: 0 0 1rem;
  color: var(--ink-soft);
  font-size: 0.9rem;
  line-height: 1.7;
}

.node-state {
  display: inline-flex;
  padding: 0.32rem 0.55rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--ink-soft);
  font-size: 0.66rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.node-state--available {
  border-color: rgba(37, 117, 94, 0.25);
  background: rgba(37, 117, 94, 0.06);
  color: var(--success);
}

/* ==========================================================================
   Knowledge formats and handoff
   ========================================================================== */

.knowledge-continuation {
  background: rgba(101, 83, 166, 0.045);
}

.knowledge-format-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.8rem;
}

.knowledge-format {
  display: flex;
  flex-direction: column;
  min-height: 280px;
  padding: 1.35rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.48);
  color: var(--ink);
  text-decoration: none;
  transition:
    border-color 160ms ease,
    background-color 160ms ease,
    transform 160ms ease;
}

a.knowledge-format:hover,
a.knowledge-format:focus-visible {
  border-color: var(--knowledge);
  background: rgba(255, 255, 255, 0.8);
  transform: translateY(-2px);
}

.knowledge-format > span {
  color: var(--knowledge);
  font-size: 0.66rem;
  letter-spacing: 0.12em;
}

.knowledge-format h3 {
  margin: 3rem 0 0.7rem;
  font-family: var(--serif);
  font-size: 1.8rem;
  font-weight: 500;
  line-height: 1.1;
}

.knowledge-format p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.86rem;
  line-height: 1.65;
}

.knowledge-format strong {
  margin-top: auto;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
  color: var(--knowledge);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.knowledge-format--forming {
  background: rgba(255, 255, 255, 0.26);
}

.knowledge-format--forming strong {
  color: var(--ink-soft);
}

.atlas-return {
  padding: clamp(4rem, 7vw, 6rem) 0;
}

.atlas-return-panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: end;
  gap: 3rem;
  padding: clamp(2rem, 5vw, 4.5rem);
  border: 1px solid rgba(31, 108, 115, 0.2);
  border-radius: var(--radius-lg);
  background:
    linear-gradient(125deg, rgba(31, 108, 115, 0.065), transparent 62%),
    rgba(255, 255, 255, 0.52);
}

.atlas-return-panel h2 {
  max-width: 800px;
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(2.6rem, 5vw, 5rem);
  font-weight: 500;
  letter-spacing: -0.04em;
  line-height: 0.98;
}

html[lang="zh-Hans"] .atlas-return-panel h2 {
  line-height: 1.12;
}

.atlas-return-panel p:not(.eyebrow) {
  max-width: 670px;
  margin: 1.4rem 0 0;
  color: var(--ink-soft);
}

.atlas-return .atlas-action--primary {
  min-width: 210px;
}

.atlas-footer {
  background: rgba(255, 255, 255, 0.18);
}

/* ==========================================================================
   Responsive layout
   ========================================================================== */

@media (max-width: 1120px) {
  .atlas-navigation {
    display: none;
  }

  .atlas-hero-layout {
    grid-template-columns: minmax(0, 1.4fr) minmax(250px, 0.6fr);
    gap: 3rem;
  }

  .book-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .book-card--three {
    grid-column: 1 / -1;
    min-height: 430px;
  }

  .knowledge-format-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 820px) {
  .atlas-shell {
    width: min(calc(100% - 2rem), var(--max));
  }

  .atlas-hero {
    min-height: auto;
    padding: 9.5rem 0 5.5rem;
  }

  .atlas-hero-layout,
  .atlas-overview-grid,
  .atlas-section-heading--wide,
  .atlas-return-panel {
    grid-template-columns: 1fr;
  }

  .atlas-hero-copy h1 {
    font-size: clamp(3.9rem, 13vw, 6.3rem);
  }

  html[lang="zh-Hans"] .atlas-hero-copy h1 {
    font-size: clamp(3.65rem, 12vw, 5.6rem);
  }

  .atlas-orientation {
    max-width: 560px;
  }

  .atlas-overview-grid,
  .atlas-section-heading--wide {
    gap: 2.2rem;
  }

  .atlas-node-grid {
    grid-template-columns: 1fr;
  }

  .atlas-filter-bar {
    position: static;
    align-items: flex-start;
    flex-direction: column;
    border-radius: var(--radius-md);
  }

  .atlas-filter-status {
    margin: 0 0.65rem 0.35rem;
  }

  .atlas-return-panel {
    align-items: start;
  }
}

@media (max-width: 620px) {
  .atlas-header {
    align-items: center;
    min-height: 68px;
    padding-top: 0;
  }

  .atlas-header .brand-wordmark {
    display: inline;
  }

  .atlas-hero {
    padding-top: 8.5rem;
  }

  .atlas-hero-orbit {
    top: 28%;
    right: -68vw;
    width: 140vw;
  }

  .atlas-hero-copy h1 {
    font-size: clamp(3.2rem, 17vw, 4.55rem);
    line-height: 0.94;
  }

  html[lang="zh-Hans"] .atlas-hero-copy h1 {
    font-size: clamp(3.05rem, 15vw, 4.2rem);
    line-height: 1.08;
  }

  .atlas-hero-actions,
  .atlas-action {
    width: 100%;
  }

  .atlas-reading-forms,
  .book-grid,
  .knowledge-format-grid {
    grid-template-columns: 1fr;
  }

  .atlas-reading-forms article:nth-child(odd),
  .atlas-reading-forms article:nth-child(even) {
    min-height: 0;
    padding: 1.4rem 0;
    border-right: 0;
  }

  .book-card,
  .book-card--three {
    grid-column: auto;
    min-height: 450px;
  }

  .atlas-filters {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    width: 100%;
  }

  .atlas-filters button {
    justify-content: space-between;
  }

  .atlas-node summary {
    grid-template-columns: 2.1rem minmax(0, 1fr) auto;
    gap: 0.75rem;
    min-height: 102px;
    padding: 1rem;
  }

  .atlas-node-index {
    font-size: 1.15rem;
  }

  .atlas-node-heading strong {
    font-size: 1.4rem;
  }

  .atlas-node-content {
    padding: 0 1rem 1.15rem 3.85rem;
  }

  .knowledge-format {
    min-height: 250px;
  }

  .atlas-return-panel {
    padding: 2rem 1.25rem;
  }

  .atlas-return .atlas-action--primary {
    min-width: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .atlas-header,
  .atlas-navigation a::after,
  .atlas-action,
  .book-card > a span:last-child,
  .atlas-node,
  .atlas-node-toggle,
  .knowledge-format {
    transition: none;
  }
}