/* Hallmark · macrostructure: Photographic · tone: atmospheric-austere · anchor hue: ink-crimson
 * theme: Midnight-ink (custom-tuned for 水墨古风 ACT) · paper dark · display: Noto Serif SC · body: Noto Sans SC
 * nav: N5 Floating pill · footer: Ft5 Statement · enrichment: full-bleed hero photography
 * pre-emit critique: P4 H4 E4 S4 R4 V4
 */
:root {
  --color-paper: oklch(16% 0.018 250);
  --color-paper-2: oklch(20% 0.02 248);
  --color-paper-3: oklch(24% 0.022 246);
  --color-ink: oklch(93% 0.015 85);
  --color-ink-muted: oklch(72% 0.02 80);
  --color-ink-faint: oklch(55% 0.02 250);
  --color-accent: oklch(58% 0.17 28);
  --color-accent-2: oklch(68% 0.08 160);
  --color-rule: oklch(32% 0.02 250);
  --color-focus: oklch(72% 0.12 85);
  --color-overlay: oklch(10% 0.02 250 / 0.62);
  --color-glow: oklch(58% 0.17 28 / 0.45);

  --font-display: "Noto Serif SC", "Songti SC", serif;
  --font-body: "Noto Sans SC", "PingFang SC", sans-serif;

  --text-display: clamp(2.75rem, 6vw, 4.5rem);
  --text-display-s: clamp(2rem, 4vw, 3rem);
  --text-4xl: clamp(1.75rem, 3vw, 2.25rem);
  --text-3xl: 1.75rem;
  --text-2xl: 1.375rem;
  --text-xl: 1.125rem;
  --text-base: 1rem;
  --text-sm: 0.875rem;
  --text-xs: 0.75rem;

  --space-2xs: 0.25rem;
  --space-xs: 0.5rem;
  --space-sm: 0.75rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4.5rem;
  --space-4xl: 6rem;

  --radius: 6px;
  --radius-pill: 999px;
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-in: cubic-bezier(0.4, 0, 1, 1);
  --ease-in-out: cubic-bezier(0.45, 0, 0.55, 1);
  --dur-fast: 150ms;
  --dur: 280ms;
  --max: 1120px;
  --nav-h: 4.25rem;
}

html {
  scroll-behavior: smooth;
  overflow-x: clip;
}

body {
  margin: 0;
  background: var(--color-paper);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.7;
  overflow-x: clip;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: inherit;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
}

a:hover {
  color: var(--color-accent);
}

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-style: normal;
  font-weight: 700;
  line-height: 1.2;
  overflow-wrap: anywhere;
  min-width: 0;
}

h1 {
  font-size: var(--text-display) !important;
  letter-spacing: 0.04em;
}

h2 {
  font-size: var(--text-4xl) !important;
}

h3 {
  font-size: var(--text-2xl) !important;
}

.container {
  width: min(100% - 2rem, var(--max));
  margin-inline: auto;
}

/* N5 floating pill nav */
.site-header {
  position: fixed;
  inset: 0.75rem 0 auto;
  z-index: 50;
  display: flex;
  justify-content: center;
  pointer-events: none;
}

.nav-shell {
  pointer-events: auto;
  display: flex;
  align-items: center;
  gap: var(--space-md);
  width: min(100% - 1.5rem, 980px);
  min-height: var(--nav-h);
  padding: 0.45rem 0.65rem 0.45rem 0.75rem;
  background: oklch(14% 0.02 250 / 0.78);
  border: 1px solid var(--color-rule);
  border-radius: var(--radius-pill);
  backdrop-filter: blur(14px);
  box-shadow: 0 10px 40px oklch(0% 0 0 / 0.35);
}

.nav-brand {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
  min-width: 0;
  flex-shrink: 0;
}

.nav-brand img {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  object-fit: cover;
  border: 1px solid var(--color-rule);
}

.nav-brand span {
  font-family: var(--font-display);
  font-size: 1.05rem;
  letter-spacing: 0.08em;
  white-space: nowrap;
}

.nav-links {
  display: none;
  align-items: center;
  gap: 0.15rem;
  list-style: none;
  margin: 0;
  padding: 0;
  flex: 1;
}

.nav-links a {
  display: inline-flex;
  align-items: center;
  padding: 0.45rem 0.7rem;
  border-radius: var(--radius-pill);
  text-decoration: none;
  color: var(--color-ink-muted);
  font-size: var(--text-sm);
  white-space: nowrap;
  transition: color var(--dur) var(--ease-out), background var(--dur) var(--ease-out);
}

.nav-links a:hover,
.nav-links a.is-active {
  color: var(--color-ink);
  background: oklch(100% 0 0 / 0.06);
}

.nav-cta {
  margin-left: auto;
  flex-shrink: 0;
}

.nav-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 50%;
  border: 1px solid var(--color-rule);
  background: transparent;
  color: var(--color-ink);
  cursor: pointer;
}

@media (min-width: 768px) {
  .nav-links { display: flex; }
  .nav-toggle { display: none; }
}

.nav-drawer {
  display: none;
  position: fixed;
  inset: 5rem 1rem auto;
  z-index: 49;
  padding: 1rem;
  background: var(--color-paper-2);
  border: 1px solid var(--color-rule);
  border-radius: 12px;
}

.nav-drawer.is-open { display: block; }

.nav-drawer a {
  display: block;
  padding: 0.75rem 0.5rem;
  text-decoration: none;
  border-bottom: 1px solid var(--color-rule);
}

/* Buttons */
.btn,
.btn-primary,
.btn-secondary,
.btn-glow {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  min-height: 2.85rem;
  padding: 0.7rem 1.35rem;
  border-radius: var(--radius);
  border: 1px solid transparent;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.04em;
  text-decoration: none !important;
  cursor: pointer;
  transition: transform var(--dur) var(--ease-out), background var(--dur) var(--ease-out), border-color var(--dur) var(--ease-out), box-shadow var(--dur) var(--ease-out);
}

.btn:active,
.btn-primary:active,
.btn-secondary:active,
.btn-glow:active {
  transform: translateY(1px);
}

.btn-primary,
.btn-glow {
  position: relative;
  overflow: hidden;
  color: oklch(98% 0.01 85) !important;
  background: linear-gradient(120deg, var(--color-accent), oklch(48% 0.16 20));
  box-shadow: 0 0 0 1px oklch(100% 0 0 / 0.08), 0 8px 28px var(--color-glow);
}

.btn-glow::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(110deg, transparent 20%, oklch(100% 0 0 / 0.35) 45%, transparent 70%);
  transform: translateX(-120%);
  animation: sheen 2.8s var(--ease-in-out) infinite;
}

@keyframes sheen {
  0%, 55% { transform: translateX(-120%); }
  100% { transform: translateX(120%); }
}

.btn-secondary {
  color: var(--color-ink) !important;
  background: oklch(100% 0 0 / 0.04);
  border-color: var(--color-rule);
}

.btn-secondary:hover {
  border-color: var(--color-ink-faint);
  background: oklch(100% 0 0 / 0.08);
}

.btn-lg {
  min-height: 3.4rem;
  padding: 0.9rem 1.8rem;
  font-size: var(--text-base);
}

/* Photographic hero */
.hero {
  position: relative;
  min-height: 100svh;
  display: grid;
  align-items: end;
  padding: calc(var(--nav-h) + 2.5rem) 0 3.5rem;
  isolation: isolate;
}

.hero-media {
  position: absolute;
  inset: 0;
  z-index: -2;
}

.hero-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center 20%;
}

.hero-media::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(180deg, oklch(10% 0.02 250 / 0.55) 0%, var(--color-overlay) 45%, var(--color-paper) 100%),
    radial-gradient(ellipse at 70% 30%, oklch(58% 0.17 28 / 0.18), transparent 55%);
}

.hero-copy {
  width: min(100% - 2rem, var(--max));
  margin-inline: auto;
}

.hero-badge {
  display: inline-flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: var(--space-md);
}

.hero-badge span {
  padding: 0.28rem 0.7rem;
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  background: oklch(100% 0 0 / 0.04);
  color: var(--color-ink-muted);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
}

.hero-en {
  margin: 0.35rem 0 0;
  color: var(--color-accent-2);
  font-family: var(--font-display);
  font-size: clamp(1rem, 2vw, 1.35rem);
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.hero-lead {
  max-width: 36rem;
  margin: 1rem 0 0;
  color: var(--color-ink-muted);
  font-size: clamp(1rem, 2vw, 1.15rem);
}

.hero-metrics {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin: 1.25rem 0 0;
  padding: 0;
  list-style: none;
}

.hero-metrics li {
  padding: 0.45rem 0.8rem;
  border-left: 2px solid var(--color-accent);
  background: oklch(100% 0 0 / 0.04);
  color: var(--color-ink-muted);
  font-size: var(--text-sm);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
}

/* Sections */
.section {
  padding: var(--space-3xl) 0;
}

.section-head {
  margin-bottom: var(--space-xl);
  max-width: 40rem;
}

.section-head p {
  margin: 0.65rem 0 0;
  color: var(--color-ink-muted);
}

.photo-band {
  position: relative;
  min-height: 58svh;
  display: grid;
  align-items: end;
}

.photo-band img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: -1;
}

.photo-band::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent, var(--color-paper));
  z-index: 0;
}

.photo-caption {
  position: relative;
  z-index: 1;
  width: min(100% - 2rem, var(--max));
  margin: 0 auto 2rem;
  color: var(--color-ink-muted);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 160px), 1fr));
  gap: 1px;
  background: var(--color-rule);
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  overflow: hidden;
}

.info-grid article {
  background: var(--color-paper-2);
  padding: 1.1rem 1rem;
}

.info-grid dt,
.info-grid .label {
  color: var(--color-ink-faint);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
}

.info-grid dd,
.info-grid .value {
  margin: 0.35rem 0 0;
  font-family: var(--font-display);
  font-size: var(--text-xl);
}

.story-block {
  max-width: 42rem;
  margin-inline: auto;
  text-align: center;
}

.story-block p {
  color: var(--color-ink-muted);
  font-size: 1.05rem;
  line-height: 1.9;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 240px), 1fr));
  gap: var(--space-md);
}

.feature-card {
  padding: 1.25rem;
  background: var(--color-paper-2);
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  transition: transform var(--dur) var(--ease-out), box-shadow var(--dur) var(--ease-out), border-color var(--dur) var(--ease-out);
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-ink-faint);
  box-shadow: 0 12px 30px oklch(0% 0 0 / 0.28);
}

.feature-card .icon {
  width: 2.25rem;
  height: 2.25rem;
  display: grid;
  place-items: center;
  margin-bottom: 0.85rem;
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  color: var(--color-accent);
  font-family: var(--font-display);
}

.feature-card p {
  margin: 0.5rem 0 0;
  color: var(--color-ink-muted);
  font-size: var(--text-sm);
}

.gallery-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem;
}

@media (min-width: 768px) {
  .gallery-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (min-width: 1024px) {
  .gallery-grid.cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

.gallery-item {
  position: relative;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  border-radius: var(--radius);
  border: 1px solid var(--color-rule);
  cursor: zoom-in;
  background: var(--color-paper-2);
  padding: 0;
}

.gallery-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--dur) var(--ease-out), filter var(--dur) var(--ease-out);
}

.gallery-item:hover img {
  transform: scale(1.04);
  filter: brightness(1.08);
}

.download-band {
  position: relative;
  padding: var(--space-3xl) 0;
  background:
    radial-gradient(ellipse at 20% 0%, oklch(58% 0.17 28 / 0.2), transparent 50%),
    var(--color-paper-2);
  border-block: 1px solid var(--color-rule);
  text-align: center;
}

.platform-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}

@media (min-width: 768px) {
  .platform-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

.platform-card {
  padding: 1.5rem;
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  background: var(--color-paper);
  text-align: left;
}

.platform-card .tag {
  display: inline-block;
  margin-bottom: 0.75rem;
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius);
  background: var(--color-accent);
  color: oklch(98% 0.01 85);
  font-size: var(--text-xs);
}

.timeline {
  display: grid;
  gap: 1rem;
}

.timeline-item {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1rem;
  padding: 1rem;
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  background: var(--color-paper-2);
}

.timeline-num {
  width: 2rem;
  height: 2rem;
  display: grid;
  place-items: center;
  border-radius: 50%;
  border: 1px solid var(--color-accent);
  color: var(--color-accent);
  font-family: var(--font-display);
}

.accordion details {
  border-bottom: 1px solid var(--color-rule);
}

.accordion summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.1rem 0;
  font-family: var(--font-display);
  font-size: var(--text-xl);
}

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

.accordion summary::after {
  content: "+";
  color: var(--color-accent);
  font-family: var(--font-body);
}

.accordion details[open] summary::after { content: "-"; }

.accordion .answer {
  padding: 0 0 1.15rem;
  color: var(--color-ink-muted);
}

.fit-grid,
.review-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}

@media (min-width: 768px) {
  .fit-grid,
  .review-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

.fit-card,
.review-card {
  padding: 1.25rem;
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  background: var(--color-paper-2);
}

.fit-card p,
.review-card p {
  color: var(--color-ink-muted);
  margin: 0.5rem 0 0;
}

.review-card footer {
  margin-top: 1rem;
  color: var(--color-ink-faint);
  font-size: var(--text-sm);
}

.final-cta {
  padding: var(--space-4xl) 0;
  text-align: center;
  background:
    linear-gradient(180deg, transparent, oklch(58% 0.17 28 / 0.08)),
    var(--color-paper);
}

.final-cta p {
  max-width: 34rem;
  margin: 0.85rem auto 0;
  color: var(--color-ink-muted);
}

.final-cta .note {
  margin-top: 1rem;
  font-size: var(--text-xs);
  color: var(--color-ink-faint);
}

/* Footer Ft5 */
.site-footer {
  padding: var(--space-3xl) 0 var(--space-xl);
  border-top: 1px solid var(--color-rule);
  background: var(--color-paper-2);
}

.footer-statement {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 3vw, 2rem);
  max-width: 28rem;
  margin: 0 0 1.5rem;
  line-height: 1.35;
}

.footer-grid {
  display: grid;
  gap: 1.5rem;
}

@media (min-width: 768px) {
  .footer-grid {
    grid-template-columns: 1.4fr 1fr 1fr;
  }
}

.footer-grid a {
  color: var(--color-ink-muted);
  text-decoration: none;
  display: inline-block;
  margin: 0.25rem 0;
  font-size: var(--text-sm);
}

.footer-grid a:hover { color: var(--color-ink); }

.footer-bottom {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--color-rule);
  color: var(--color-ink-faint);
  font-size: var(--text-xs);
}

/* Lightbox */
.lightbox {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: none;
  place-items: center;
  background: oklch(5% 0.02 250 / 0.88);
  padding: 1rem;
}

.lightbox.is-open { display: grid; }

.lightbox img {
  max-width: min(96vw, 1100px);
  max-height: 82vh;
  object-fit: contain;
  border-radius: var(--radius);
}

.lightbox-close,
.lightbox-nav {
  position: absolute;
  border: 1px solid var(--color-rule);
  background: var(--color-paper-2);
  color: var(--color-ink);
  cursor: pointer;
  border-radius: var(--radius);
}

.lightbox-close {
  top: 1rem;
  right: 1rem;
  width: 2.5rem;
  height: 2.5rem;
}

.lightbox-nav {
  top: 50%;
  transform: translateY(-50%);
  width: 2.75rem;
  height: 2.75rem;
}

.lightbox-prev { left: 1rem; }
.lightbox-next { right: 1rem; }

/* Tabs / modal */
.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 1.25rem;
}

.tab-btn {
  padding: 0.45rem 0.9rem;
  border-radius: var(--radius-pill);
  border: 1px solid var(--color-rule);
  background: transparent;
  color: var(--color-ink-muted);
  cursor: pointer;
  font-size: var(--text-sm);
}

.tab-btn.is-active,
.tab-btn:hover {
  color: var(--color-ink);
  border-color: var(--color-accent);
  background: oklch(58% 0.17 28 / 0.12);
}

.modal {
  position: fixed;
  inset: 0;
  z-index: 70;
  display: none;
  place-items: center;
  padding: 1rem;
  background: oklch(5% 0.02 250 / 0.8);
}

.modal.is-open { display: grid; }

.modal-panel {
  width: min(100%, 720px);
  max-height: 85vh;
  overflow: auto;
  padding: 1.5rem;
  background: var(--color-paper-2);
  border: 1px solid var(--color-rule);
  border-radius: 8px;
}

.modal-panel table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: var(--text-sm);
}

.modal-panel th,
.modal-panel td {
  border: 1px solid var(--color-rule);
  padding: 0.55rem 0.65rem;
  text-align: left;
}

.guide-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}

@media (min-width: 768px) {
  .guide-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

.guide-card {
  text-align: left;
  padding: 1.25rem;
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  background: var(--color-paper-2);
  cursor: pointer;
  transition: transform var(--dur) var(--ease-out), border-color var(--dur) var(--ease-out);
}

.guide-card:hover {
  transform: translateY(-3px);
  border-color: var(--color-accent);
}

.req-grid {
  display: grid;
  gap: 1rem;
}

@media (min-width: 768px) {
  .req-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

.req-card {
  padding: 1.25rem;
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  background: var(--color-paper-2);
}

.req-card ul {
  margin: 0.75rem 0 0;
  padding-left: 1.1rem;
  color: var(--color-ink-muted);
}

.article-list {
  display: grid;
  gap: 0.75rem;
}

.article-list a {
  display: block;
  padding: 0.9rem 1rem;
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  text-decoration: none;
  background: var(--color-paper-2);
}

.prose-article {
  max-width: 46rem;
  margin: 0 auto;
}

.prose-article p,
.prose-article li {
  color: var(--color-ink-muted);
}

.prose-article table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.25rem 0;
}

.prose-article th,
.prose-article td {
  border: 1px solid var(--color-rule);
  padding: 0.55rem 0.7rem;
  text-align: left;
}

.page-hero {
  padding: calc(var(--nav-h) + 3rem) 0 2rem;
}

.reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.5s var(--ease-out), transform 0.5s var(--ease-out);
}

.reveal.is-in {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .btn-glow::after { animation: none; }
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
  .feature-card:hover,
  .guide-card:hover,
  .gallery-item:hover img {
    transform: none;
  }
}