@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

:root {
  --u: 8px;
  --ink: #000000;
  --paper: #ffffff;
  --line: #000000;
  --wrap: 1240px;
  --font: 'Inter', 'Helvetica Neue', Helvetica, Arial, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --nav-h: 60px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  overflow-x: hidden;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font);
  font-size: 1rem;
  line-height: 1.7;
  font-weight: 400;
  letter-spacing: 0.012em;
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: inherit;
}

button,
input {
  font: inherit;
}

.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding-left: calc(var(--u) * 2);
  padding-right: calc(var(--u) * 2);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ---------- header ---------- */

.site-head {
  background: var(--paper);
  border-bottom: 1px solid var(--line);
}

.head-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--u);
  padding-top: calc(var(--u) * 1.5);
  padding-bottom: calc(var(--u) * 1.5);
}

.brand {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  text-decoration: none;
}

.logo-mark {
  width: 28px;
  height: 28px;
  object-fit: contain;
}

.logo-text {
  font-size: 0.9375rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.head-cta {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 calc(var(--u) * 2);
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 0.9375rem;
  font-weight: 500;
  text-decoration: none;
  white-space: nowrap;
  transition: background 0.18s linear, color 0.18s linear;
}

.head-cta:hover,
.head-cta:focus-visible {
  background: var(--ink);
  color: var(--paper);
}

.anchors {
  position: sticky;
  top: 0;
  z-index: 40;
  border-top: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.76);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  backdrop-filter: blur(14px) saturate(140%);
}

.anchors p {
  display: flex;
  gap: var(--u);
  max-width: var(--wrap);
  margin: 0 auto;
  padding: var(--u) calc(var(--u) * 2);
  overflow-x: auto;
  scrollbar-width: none;
}

.anchors p::-webkit-scrollbar {
  display: none;
}

.anchors a {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 calc(var(--u) * 1.75);
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.6);
  font-size: 0.9375rem;
  font-weight: 500;
  white-space: nowrap;
  text-decoration: none;
  transition: background 0.18s linear, color 0.18s linear;
}

.anchors a:hover,
.anchors a:focus-visible {
  background: var(--ink);
  color: var(--paper);
}

/* ---------- hero ---------- */

.hero {
  position: relative;
  display: flex;
  align-items: flex-end;
  height: 45vh;
  min-height: 340px;
  overflow: hidden;
  background: var(--ink);
  color: var(--paper);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 44px), 0 100%);
}

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

.hero-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: grayscale(1) contrast(1.08);
}

.hero-media::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, rgba(0, 0, 0, 0.22), rgba(0, 0, 0, 0.86));
}

.hero-veil {
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(90deg, #000 0 6px, #141414 6px 12px);
}

.hero-cap {
  position: absolute;
  left: calc(var(--u) * 2);
  bottom: calc(var(--u) * 7);
  z-index: 2;
  margin: 0;
  font-size: 0.875rem;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  opacity: 0.85;
}

.hero-copy {
  position: relative;
  z-index: 2;
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: calc(var(--u) * 6) calc(var(--u) * 2) calc(var(--u) * 10);
  text-align: right;
}

.hero h1 {
  margin: 0;
  font-size: clamp(2rem, 7.2vw, 4.5rem);
  line-height: 1.14;
  font-weight: 700;
  letter-spacing: -0.035em;
}

/* ---------- hero split (default) ---------- */

.hero-split {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: calc(var(--u) * 2);
  align-items: center;
  padding-top: calc(var(--u) * 6);
  padding-bottom: calc(var(--u) * 6);
}

.hero-split .hero-copy {
  grid-column: 1 / span 7;
  padding: 0;
  text-align: left;
  color: var(--ink);
  max-width: none;
}

.hero-split h1 {
  font-size: clamp(1.875rem, 5vw, 3.25rem);
}

.hero-kicker {
  margin: 0 0 var(--u);
  font-size: 0.875rem;
  font-weight: 500;
  letter-spacing: 0.24em;
  text-transform: uppercase;
}

.hero-split .hero-media {
  position: relative;
  inset: auto;
  grid-column: 8 / span 5;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  background: var(--ink);
}

/* ---------- body grid ---------- */

.body-grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: calc(var(--u) * 3);
  align-items: start;
  padding-top: calc(var(--u) * 7);
  padding-bottom: calc(var(--u) * 10);
}

.flow {
  grid-column: 1 / span 8;
  min-width: 0;
}

.flow-title {
  margin: 0 0 var(--u);
  font-size: clamp(1.5rem, 3.2vw, 2.125rem);
  line-height: 1.22;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.subtitle {
  max-width: 60ch;
  margin: 0 0 calc(var(--u) * 4);
  padding-bottom: calc(var(--u) * 2);
  border-bottom: 1px solid var(--line);
  font-size: 1.0625rem;
  line-height: 1.7;
}

/* ---------- rail ---------- */

.rail {
  grid-column: 10 / span 3;
  position: sticky;
  top: calc(var(--nav-h) + var(--u) * 2);
  padding: calc(var(--u) * 2);
  background: rgba(255, 255, 255, 0.72);
  -webkit-backdrop-filter: blur(12px) saturate(150%);
  backdrop-filter: blur(12px) saturate(150%);
  border: 1px solid var(--line);
}

.rail-label {
  margin: 0 0 calc(var(--u) * 1.5);
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.22em;
}

.rail-list {
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: rail;
}

.rail-list li {
  counter-increment: rail;
}

.rail-list a {
  display: flex;
  gap: var(--u);
  align-items: baseline;
  min-height: 44px;
  padding: calc(var(--u) * 0.9) 0;
  border-bottom: 1px solid rgba(0, 0, 0, 0.14);
  font-size: 0.9375rem;
  line-height: 1.5;
  text-decoration: none;
}

.rail-list a::before {
  content: counter(rail, decimal-leading-zero);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  opacity: 0.55;
}

.rail-list a:hover,
.rail-list a.on {
  font-weight: 600;
}

.rail-list a.on::before {
  opacity: 1;
}

/* ---------- prose ---------- */

.prose {
  counter-reset: sec;
  font-size: 1.0625rem;
  line-height: 1.85;
}

.prose > section {
  counter-increment: sec;
  position: relative;
  margin-top: calc(var(--u) * 6);
  padding-top: calc(var(--u) * 4);
  border-top: 1px solid var(--line);
  scroll-margin-top: calc(var(--nav-h) + var(--u) * 4);
}

.prose > section::before {
  content: counter(sec, decimal-leading-zero);
  display: block;
  margin-bottom: var(--u);
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.2em;
}

.prose h2 {
  margin: 0 0 calc(var(--u) * 2);
  font-size: clamp(1.375rem, 2.6vw, 1.875rem);
  line-height: 1.25;
  font-weight: 700;
  letter-spacing: -0.018em;
}

.prose h3 {
  margin: calc(var(--u) * 3) 0 var(--u);
  font-size: 1.1875rem;
  line-height: 1.35;
  font-weight: 600;
}

.prose p {
  margin: 0 0 calc(var(--u) * 2);
}

.prose ul,
.prose ol {
  margin: 0 0 calc(var(--u) * 2);
  padding-left: calc(var(--u) * 3);
}

.prose li {
  margin-bottom: calc(var(--u) * 0.6);
}

.prose a {
  text-decoration: underline;
  text-underline-offset: 3px;
}

.prose figure {
  margin: calc(var(--u) * 3) 0;
  padding: var(--u);
  border: 1px solid var(--line);
  background: rgba(0, 0, 0, 0.03);
}

.prose figure img {
  width: 100%;
}

.prose figcaption {
  padding-top: var(--u);
  font-size: 0.875rem;
  line-height: 1.6;
}

.prose aside {
  margin: calc(var(--u) * 3) 0;
  padding: var(--u) calc(var(--u) * 2);
  border-left: 3px solid var(--ink);
  background: rgba(0, 0, 0, 0.04);
}

.prose blockquote {
  margin: calc(var(--u) * 3) 0;
  padding-left: calc(var(--u) * 2.5);
  border-left: 1px solid var(--line);
  font-size: 1.125rem;
}

.prose table {
  width: 100%;
  border-collapse: collapse;
  font-size: 1rem;
}

.prose th,
.prose td {
  padding: var(--u);
  border-bottom: 1px solid var(--line);
  text-align: left;
}

.prose code {
  font-family: ui-monospace, 'SFMono-Regular', Menlo, monospace;
  font-size: 0.9375rem;
}

/* ---------- footer ---------- */

.site-foot {
  background: var(--ink);
  color: var(--paper);
  border-top: 1px solid var(--line);
}

.foot-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: calc(var(--u) * 4);
  padding-top: calc(var(--u) * 7);
  padding-bottom: calc(var(--u) * 6);
}

.foot-brand p {
  margin: 0 0 var(--u);
}

.foot-name {
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.sub-form {
  display: flex;
  flex-wrap: wrap;
  gap: var(--u);
  margin-top: calc(var(--u) * 2);
}

.sub-form input {
  flex: 1 1 120px;
  min-height: 44px;
  padding: 0 calc(var(--u) * 1.5);
  border: 1px solid rgba(255, 255, 255, 0.55);
  border-radius: 0;
  background: transparent;
  color: var(--paper);
  font-size: 0.9375rem;
}

.sub-form input::placeholder {
  color: rgba(255, 255, 255, 0.62);
}

.sub-form button {
  min-height: 44px;
  padding: 0 calc(var(--u) * 2);
  border: 1px solid var(--paper);
  border-radius: 999px;
  background: var(--paper);
  color: var(--ink);
  font-size: 0.9375rem;
  font-weight: 500;
  cursor: pointer;
}

.sub-form button:hover,
.sub-form button:focus-visible {
  background: transparent;
  color: var(--paper);
}

.site-foot dl {
  margin: 0;
}

.site-foot dt {
  padding-bottom: var(--u);
  border-bottom: 1px solid rgba(255, 255, 255, 0.42);
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.2em;
}

.site-foot dd {
  margin: var(--u) 0 0;
}

.site-foot dd a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  font-size: 0.9375rem;
  text-decoration: none;
  opacity: 0.86;
}

.site-foot dd a:hover,
.site-foot dd a:focus-visible {
  opacity: 1;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.foot-copy {
  margin: 0;
  padding: calc(var(--u) * 3) calc(var(--u) * 2);
  border-top: 1px solid rgba(255, 255, 255, 0.3);
  font-size: 0.875rem;
  letter-spacing: 0.1em;
  text-align: center;
}

/* ---------- back to top ---------- */

.to-top {
  position: fixed;
  right: calc(var(--u) * 2);
  bottom: calc(var(--u) * 2);
  z-index: 60;
  min-height: 44px;
  padding: 0 calc(var(--u) * 2);
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--paper);
  color: var(--ink);
  font-size: 0.875rem;
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s linear;
}

.to-top.on {
  opacity: 1;
  pointer-events: auto;
}

/* ---------- reveal ---------- */

.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.55s ease-out, transform 0.55s cubic-bezier(0.22, 0.68, 0.25, 1);
  will-change: opacity, transform;
}

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

/* ---------- responsive ---------- */

@media (max-width: 900px) {
  .body-grid {
    grid-template-columns: 1fr;
    gap: calc(var(--u) * 4);
  }

  .flow,
  .rail {
    grid-column: 1 / -1;
  }

  .rail {
    position: static;
    order: 2;
  }

  .flow {
    order: 1;
  }

  .hero-split .hero-copy,
  .hero-split .hero-media {
    grid-column: 1 / -1;
  }

  .foot-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: calc(var(--u) * 3);
  }
}

@media (max-width: 560px) {
  .hero {
    height: auto;
    min-height: 380px;
  }

  .hero-copy {
    padding-top: calc(var(--u) * 12);
    padding-bottom: calc(var(--u) * 12);
  }

  .hero-cap {
    bottom: calc(var(--u) * 4);
  }

  .foot-grid {
    grid-template-columns: 1fr;
  }

  .to-top {
    right: var(--u);
    bottom: var(--u);
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

button[aria-expanded]{min-width:44px;min-height:44px}