:root {
  --bg: #f5f7fa;
  --surface: #ffffff;
  --surface-2: #eef3f7;
  --text: #17202a;
  --muted: #5f6f7d;
  --line: #d9e2ea;
  --blue: #0b66a0;
  --blue-dark: #073d63;
  --green: #257c68;
  --amber: #b46b15;
  --shadow: 0 18px 44px rgba(19, 33, 46, 0.12);
  --radius: 8px;
  color-scheme: light;
  font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-size: 16px;
  line-height: 1.68;
}

a {
  color: inherit;
  text-decoration: none;
}

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

.site-header {
  align-items: center;
  backdrop-filter: saturate(1.2) blur(14px);
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid rgba(217, 226, 234, 0.78);
  display: flex;
  height: 78px;
  justify-content: space-between;
  left: 0;
  padding: 0 clamp(18px, 4vw, 54px);
  position: fixed;
  right: 0;
  top: 0;
  transition: box-shadow 180ms ease, background 180ms ease, height 180ms ease;
  z-index: 10;
}

.site-header.scrolled {
  background: rgba(255, 255, 255, 0.98);
  height: 66px;
  box-shadow: 0 8px 26px rgba(25, 38, 52, 0.1);
}

.brand {
  align-items: center;
  display: inline-flex;
}

.brand img {
  height: 58px;
  transition: height 180ms ease;
  width: auto;
}

.site-header.scrolled .brand img {
  height: 48px;
}

.site-nav {
  align-items: center;
  display: flex;
  gap: 4px;
}

.site-nav a {
  border-radius: 6px;
  color: #263746;
  font-size: 0.95rem;
  font-weight: 700;
  padding: 8px 12px;
}

.site-nav a:hover,
.site-nav a:focus-visible {
  background: #e8f1f8;
  color: var(--blue-dark);
  outline: none;
}

.site-nav .nav-cta {
  background: var(--blue);
  color: #fff;
  margin-left: 8px;
}

.site-nav .nav-cta:hover,
.site-nav .nav-cta:focus-visible {
  background: var(--blue-dark);
  color: #fff;
}

.nav-toggle {
  background: transparent;
  border: 0;
  display: none;
  height: 42px;
  padding: 9px;
  width: 42px;
}

.nav-toggle span {
  background: var(--text);
  display: block;
  height: 2px;
  margin: 5px 0;
  width: 24px;
}

.hero {
  align-items: center;
  background-image:
    linear-gradient(90deg, rgba(245, 247, 250, 0.96) 0%, rgba(245, 247, 250, 0.86) 42%, rgba(245, 247, 250, 0.25) 100%),
    url("./images/ivp-cover-model.png");
  background-position: center right;
  background-repeat: no-repeat;
  background-size: cover;
  display: flex;
  min-height: 74vh;
  padding: 110px clamp(20px, 6vw, 76px) 58px;
  transition: background-position 120ms linear;
}

.hero-inner {
  max-width: 760px;
}

.eyebrow,
.section-kicker {
  color: var(--green);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0;
  margin: 0 0 12px;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  letter-spacing: 0;
  line-height: 1.22;
  margin: 0;
}

h1 {
  color: #111820;
  font-size: clamp(2.4rem, 5.5vw, 5.6rem);
  max-width: 760px;
}

h2 {
  color: #14212d;
  font-size: clamp(1.7rem, 3vw, 2.65rem);
}

h3 {
  color: #162533;
  font-size: 1.15rem;
}

.hero-copy {
  color: #314150;
  font-size: clamp(1.02rem, 1.7vw, 1.24rem);
  margin: 22px 0 0;
  max-width: 670px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.button {
  align-items: center;
  border: 1px solid transparent;
  border-radius: 7px;
  display: inline-flex;
  font-weight: 800;
  justify-content: center;
  min-height: 46px;
  padding: 10px 18px;
}

.button.primary {
  background: var(--blue);
  color: #fff;
}

.button.secondary {
  background: rgba(255, 255, 255, 0.86);
  border-color: #cbd9e4;
  color: var(--blue-dark);
}

.button:hover,
.button:focus-visible {
  box-shadow: 0 10px 24px rgba(14, 72, 112, 0.18);
  outline: none;
  transform: translateY(-1px);
}

.hero-facts {
  display: grid;
  gap: 1px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin: 38px 0 0;
  max-width: 620px;
  overflow: hidden;
}

.hero-facts div {
  background: rgba(255, 255, 255, 0.82);
  border: 1px solid rgba(207, 220, 231, 0.85);
  min-height: 90px;
  padding: 14px 16px;
}

.hero-facts dt {
  color: var(--muted);
  font-size: 0.85rem;
  margin-bottom: 5px;
}

.hero-facts dd {
  color: #14202a;
  font-size: 1.08rem;
  font-weight: 800;
  margin: 0;
}

.section,
.section-band {
  padding: 82px clamp(20px, 5vw, 72px);
}

.section-inner {
  margin: 0 auto;
  max-width: 1180px;
}

.section-band {
  background: #111820;
  color: #d8e5ee;
  padding-bottom: 42px;
  padding-top: 42px;
}

.overview-grid {
  display: grid;
  gap: 42px;
  grid-template-columns: minmax(240px, 0.7fr) minmax(0, 1.3fr);
}

.overview h2 {
  color: #fff;
}

.overview p:last-child {
  font-size: 1.05rem;
  margin: 0;
}

.section-heading {
  align-items: end;
  display: flex;
  gap: 28px;
  justify-content: space-between;
  margin-bottom: 34px;
}

.section-heading h2 {
  max-width: 760px;
}

.feature-grid {
  display: grid;
  gap: 18px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.feature-item,
.spec-card,
.install-notes div,
.doc-link {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: 0 10px 28px rgba(26, 40, 52, 0.06);
}

.feature-item {
  min-height: 190px;
  padding: 22px;
}

.feature-item p,
.spec-card p,
.install-notes p,
.docs p,
.split p {
  color: var(--muted);
  margin: 12px 0 0;
}

.alt {
  background: var(--surface-2);
}

.split {
  align-items: center;
  display: grid;
  gap: 44px;
  grid-template-columns: minmax(280px, 0.85fr) minmax(0, 1.15fr);
}

.model-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 26px;
}

.tab-button {
  background: #fff;
  border: 1px solid #c8d8e4;
  border-radius: 7px;
  color: #284050;
  cursor: pointer;
  font: inherit;
  font-weight: 800;
  min-height: 42px;
  padding: 8px 14px;
}

.tab-button.active,
.tab-button:hover,
.tab-button:focus-visible {
  background: var(--blue);
  border-color: var(--blue);
  color: #fff;
  outline: none;
}

.model-view {
  background: #fff;
  border: 1px solid #d7e2ea;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.model-view img {
  aspect-ratio: 16 / 8;
  object-fit: cover;
  width: 100%;
}

.model-view p {
  color: #465867;
  margin: 0;
  padding: 16px 18px 18px;
}

.spec-layout {
  display: grid;
  gap: 18px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.spec-card {
  padding: 22px;
}

table {
  border-collapse: collapse;
  margin-top: 16px;
  width: 100%;
}

th,
td {
  border-bottom: 1px solid #d9e3ea;
  padding: 10px 0;
  text-align: left;
  vertical-align: top;
}

th {
  color: #253745;
  font-weight: 800;
  padding-right: 18px;
  width: 34%;
}

td {
  color: #516272;
}

.diagram-grid,
.gallery {
  display: grid;
  gap: 18px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

figure {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  margin: 0;
  overflow: hidden;
}

figure img {
  background: #fff;
  height: 330px;
  object-fit: contain;
  padding: 18px;
  width: 100%;
}

figcaption {
  border-top: 1px solid var(--line);
  color: #475a69;
  font-size: 0.93rem;
  font-weight: 700;
  padding: 12px 16px;
}

.install-notes {
  display: grid;
  gap: 18px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 18px;
}

.install-notes div {
  padding: 20px;
}

.gallery {
  grid-template-columns: 1fr 1fr 0.8fr;
}

.gallery figure img {
  height: 280px;
}

.operation-layout {
  display: grid;
  gap: 22px;
  grid-template-columns: minmax(300px, 0.9fr) minmax(0, 1.1fr);
}

.operation-media {
  display: grid;
  gap: 18px;
}

.operation-media figure img {
  height: 245px;
}

.operation-content {
  display: grid;
  gap: 16px;
}

.operation-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: 0 10px 28px rgba(26, 40, 52, 0.06);
  padding: 20px;
}

.key-grid {
  display: grid;
  gap: 10px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: 14px;
}

.key-grid div {
  align-items: center;
  background: #f2f6f9;
  border: 1px solid #d8e4ec;
  border-radius: 7px;
  display: grid;
  gap: 12px;
  grid-template-columns: 44px 1fr;
  min-height: 64px;
  padding: 10px;
}

.key-grid strong {
  align-items: center;
  background: #10202c;
  border-radius: 6px;
  color: #fff;
  display: inline-flex;
  font-size: 1.2rem;
  height: 40px;
  justify-content: center;
  width: 40px;
}

.key-grid span,
.operation-steps,
.warning-card p {
  color: var(--muted);
  margin: 0;
}

.operation-steps {
  padding-left: 1.25rem;
}

.operation-steps li {
  margin: 6px 0;
}

.operation-card code {
  background: #edf4f8;
  border: 1px solid #d5e3ed;
  border-radius: 5px;
  color: #0b4d7a;
  font-weight: 800;
  padding: 1px 5px;
}

.warning-card {
  border-color: #e4c58d;
  background: #fffaf1;
}

.docs {
  background: #10202c;
  color: #e6eef5;
}

.docs h2 {
  color: #fff;
}

.docs .section-kicker {
  color: #75c0ad;
}

.docs-layout {
  align-items: center;
  display: grid;
  gap: 34px;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 0.9fr);
}

.doc-actions {
  display: grid;
  gap: 14px;
}

.doc-link {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.18);
  color: #fff;
  padding: 20px;
}

.doc-link span {
  color: #9fb2c2;
  display: block;
  font-size: 0.9rem;
  margin-bottom: 6px;
}

.doc-link strong {
  display: block;
  font-size: 1.18rem;
}

.doc-link:hover,
.doc-link:focus-visible {
  background: rgba(255, 255, 255, 0.14);
  outline: 2px solid rgba(117, 192, 173, 0.55);
}

.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 620ms ease, transform 620ms ease;
  will-change: opacity, transform;
}

.reveal.in-view {
  opacity: 1;
  transform: translateY(0);
}

.feature-item.reveal,
.spec-card.reveal,
.install-notes div.reveal,
.gallery figure.reveal,
.diagram-grid figure.reveal,
.operation-media figure.reveal,
.operation-card.reveal,
.doc-link.reveal {
  transition-delay: var(--reveal-delay, 0ms);
}

.site-footer {
  align-items: center;
  background: #07111a;
  color: #c4d0da;
  display: flex;
  justify-content: space-between;
  padding: 24px clamp(20px, 5vw, 72px);
}

.site-footer div {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.site-footer a {
  color: #fff;
  font-weight: 800;
}

@media (max-width: 960px) {
  .nav-toggle {
    display: block;
  }

  .site-nav {
    align-items: stretch;
    background: #fff;
    border-bottom: 1px solid var(--line);
    box-shadow: var(--shadow);
    display: none;
    flex-direction: column;
    left: 0;
    padding: 14px 20px 20px;
    position: absolute;
    right: 0;
    top: 78px;
  }

  .site-header.scrolled .site-nav {
    top: 66px;
  }

  .site-nav.open {
    display: flex;
  }

  .site-nav .nav-cta {
    margin-left: 0;
  }

  .hero {
    background-position: 62% center;
    min-height: 76vh;
  }

  .overview-grid,
  .split,
  .docs-layout {
    grid-template-columns: 1fr;
  }

  .feature-grid,
  .spec-layout,
  .install-notes,
  .operation-layout,
  .key-grid,
  .diagram-grid,
  .gallery {
    grid-template-columns: 1fr;
  }

  .section-heading {
    align-items: start;
    flex-direction: column;
  }
}

@media (max-width: 620px) {
  .site-header {
    height: 70px;
  }

  .site-header.scrolled {
    height: 62px;
  }

  .site-nav {
    top: 70px;
  }

  .site-header.scrolled .site-nav {
    top: 62px;
  }

  .brand img {
    height: 50px;
  }

  .site-header.scrolled .brand img {
    height: 44px;
  }

  .hero {
    background-position: center bottom;
    min-height: 78vh;
    padding: 92px 20px 42px;
  }

  .hero-facts {
    grid-template-columns: 1fr;
  }

  .section,
  .section-band {
    padding: 56px 20px;
  }

  figure img {
    height: 240px;
  }

  .site-footer {
    align-items: flex-start;
    flex-direction: column;
    gap: 14px;
  }
}

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

  .site-header,
  .brand img,
  .hero,
  .button,
  .reveal {
    transition: none;
  }

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

}