:root {
  --ink: #172033;
  --muted: #5d6678;
  --line: #e1e7ef;
  --soft: #f5f8fb;
  --brand: #0b4a86;
  --brand-2: #1769aa;
  --accent: #d86f27;
  --metal: #7a8796;
  --white: #fff;
  --max: 1180px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: Arial, "Microsoft YaHei", "PingFang SC", sans-serif;
  line-height: 1.72;
  background: #fff;
}

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

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

a:focus-visible,
button:focus-visible {
  outline: 3px solid #f2a65a;
  outline-offset: 3px;
}

.container {
  width: min(var(--max), calc(100% - 32px));
  margin: 0 auto;
}

.topbar {
  background: #101827;
  color: #dce7f5;
  font-size: 14px;
}

.topbar .container,
.nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}

.nav {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, .96);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}

.brand {
  display: flex;
  flex-direction: column;
  padding: 14px 0;
}

.brand strong {
  color: var(--brand);
  font-size: 22px;
  line-height: 1.1;
}

.brand span {
  color: var(--muted);
  font-size: 13px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 18px;
  font-size: 15px;
}

.nav-links a {
  white-space: nowrap;
  color: #263246;
}

.menu-btn {
  display: none;
  width: 44px;
  height: 44px;
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 6px;
  color: var(--brand);
  font-size: 22px;
}

.hero {
  min-height: 650px;
  display: grid;
  align-items: end;
  color: #fff;
  background:
    linear-gradient(90deg, rgba(10, 20, 34, .88), rgba(10, 20, 34, .55), rgba(10, 20, 34, .18)),
    url("../images/case-wall-01.jpg") center / cover no-repeat;
}

.hero-inner {
  padding: 88px 0 58px;
}

.eyebrow {
  color: #b9d7f5;
  font-weight: 700;
  letter-spacing: 0;
}

.hero h1,
.page-hero h1 {
  max-width: 820px;
  margin: 12px 0 16px;
  font-size: clamp(34px, 5vw, 58px);
  line-height: 1.16;
  letter-spacing: 0;
}

.hero p,
.page-hero p {
  max-width: 720px;
  margin: 0 0 28px;
  color: #e9f0f8;
  font-size: 19px;
}

.hero-actions,
.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 11px 18px;
  border-radius: 6px;
  border: 1px solid transparent;
  font-weight: 700;
}

.btn.primary {
  background: var(--accent);
  color: #fff;
}

.btn.secondary {
  background: #fff;
  color: var(--brand);
}

.btn.ghost {
  border-color: rgba(255, 255, 255, .72);
  color: #fff;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  max-width: 900px;
  margin-top: 54px;
  background: rgba(255, 255, 255, .24);
  border: 1px solid rgba(255, 255, 255, .24);
}

.hero-stats div {
  padding: 18px;
  background: rgba(12, 26, 43, .62);
}

.hero-stats strong {
  display: block;
  font-size: 24px;
}

.section {
  padding: 72px 0;
}

.section.alt {
  background: var(--soft);
}

.section-head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 28px;
}

.section-head h2,
.content h2 {
  margin: 0;
  font-size: clamp(26px, 3vw, 38px);
  line-height: 1.24;
}

.section-head p {
  max-width: 620px;
  margin: 0;
  color: var(--muted);
}

.grid-2 {
  display: grid;
  grid-template-columns: 1.04fr .96fr;
  gap: 34px;
  align-items: center;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

.card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  overflow: hidden;
}

.card-body {
  padding: 22px;
}

.card h2,
.card h3 {
  margin: 0 0 8px;
  font-size: 20px;
}

.card p {
  margin: 0;
  color: var(--muted);
}

.photo {
  border-radius: 8px;
  overflow: hidden;
  background: #dfe6ee;
}

.photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.ratio-16 {
  aspect-ratio: 16 / 10;
}

.ratio-4 {
  aspect-ratio: 4 / 3;
}

.feature-list {
  display: grid;
  gap: 14px;
}

.feature {
  display: grid;
  grid-template-columns: 44px 1fr;
  gap: 14px;
  align-items: start;
}

.feature b {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 6px;
  background: #e8f2fb;
  color: var(--brand);
}

.steps {
  counter-reset: step;
  display: grid;
  gap: 14px;
}

.step {
  counter-increment: step;
  display: grid;
  grid-template-columns: 62px 1fr;
  gap: 16px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.step:before {
  content: counter(step, decimal-leading-zero);
  display: grid;
  place-items: center;
  width: 62px;
  height: 62px;
  border-radius: 6px;
  background: #eef5fb;
  color: var(--brand);
  font-size: 24px;
  font-weight: 800;
}

.step h2,
.step h3 {
  margin: 0 0 6px;
  font-size: 18px;
}

.spec-table {
  width: 100%;
  border-collapse: collapse;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.spec-table th,
.spec-table td {
  padding: 14px 16px;
  border-bottom: 1px solid var(--line);
  text-align: left;
}

.spec-table th {
  width: 34%;
  background: #eef4fa;
  color: var(--brand);
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.tag {
  padding: 8px 12px;
  border-radius: 999px;
  background: #eef4fa;
  color: #29435f;
  font-weight: 700;
}

.faq-item {
  border-bottom: 1px solid var(--line);
  padding: 18px 0;
}

.faq-item h2,
.faq-item h3 {
  margin: 0 0 8px;
  font-size: 18px;
}

.faq-item p {
  margin: 0;
  color: var(--muted);
}

.page-hero {
  color: #fff;
  background:
    linear-gradient(90deg, rgba(12, 24, 40, .92), rgba(12, 24, 40, .5)),
    url("../images/install-site-01.jpg") center / cover no-repeat;
}

.page-hero .container {
  padding: 86px 0;
}

.breadcrumb {
  color: #d3e3f3;
  font-size: 14px;
}

.content {
  max-width: 880px;
  margin: 0 auto;
}

.content p,
.content li {
  color: var(--muted);
}

.content img {
  border-radius: 8px;
  margin: 24px 0;
}

.article-list {
  display: grid;
  gap: 16px;
}

.article-list a {
  display: block;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.footer {
  background: #101827;
  color: #dce7f5;
  padding: 42px 0 26px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.2fr .8fr .8fr;
  gap: 28px;
}

.footer a,
.footer p {
  color: #c7d4e4;
}

.footer h2,
.footer h3 {
  color: #fff;
  margin-top: 0;
}

.copyright {
  margin-top: 30px;
  padding-top: 18px;
  border-top: 1px solid rgba(255, 255, 255, .15);
  color: #9eacc0;
  font-size: 14px;
}

.copyright a {
  text-decoration: underline;
  text-decoration-color: transparent;
  text-underline-offset: 3px;
  transition: text-decoration-color .2s ease;
}

.copyright a:hover,
.copyright a:focus-visible {
  text-decoration-color: currentColor;
}

@media (max-width: 900px) {
  .nav-links {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 73px;
    flex-direction: column;
    align-items: flex-start;
    padding: 18px 24px 24px;
    background: #fff;
    border-bottom: 1px solid var(--line);
  }

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

  .menu-btn {
    display: block;
  }

  .hero {
    min-height: 590px;
  }

  .hero-stats,
  .grid-2,
  .grid-3,
  .footer-grid {
    grid-template-columns: 1fr;
  }

  .section-head {
    display: block;
  }
}

@media (max-width: 560px) {
  .topbar .container {
    display: block;
    padding: 8px 0;
  }

  .hero h1,
  .page-hero h1 {
    font-size: 34px;
  }

  .hero p,
  .page-hero p {
    font-size: 17px;
  }

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