:root {
  --bg: #f7fbff;
  --surface: #ffffff;
  --surface-soft: #eef8ff;
  --surface-strong: #d9f0ff;
  --text: #153047;
  --muted: #5c7890;
  --line: rgba(38, 125, 189, 0.14);
  --primary: #33a9ff;
  --primary-dark: #1488de;
  --shadow: 0 22px 60px rgba(44, 120, 180, 0.12);
  --radius-lg: 28px;
  --radius-md: 18px;
  --radius-sm: 12px;
  --max-width: 1180px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(94, 201, 255, 0.15), transparent 30%),
    linear-gradient(180deg, #ffffff 0%, var(--bg) 100%);
  line-height: 1.65;
}

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

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

p, ul {
  margin-top: 0;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: auto;
}

.skip-link:focus {
  left: 20px;
  top: 16px;
  z-index: 1000;
  background: #fff;
  color: var(--text);
  padding: 10px 14px;
  border-radius: 10px;
  box-shadow: var(--shadow);
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(18px);
  background: rgba(255, 255, 255, 0.86);
  border-bottom: 1px solid rgba(38, 125, 189, 0.08);
}

.header-inner {
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  gap: 28px;
  min-height: 92px;
  padding: 14px 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 14px;
  min-width: 0;
}

.brand-logo {
  width: 54px;
  height: 54px;
  object-fit: contain;
  flex: 0 0 auto;
}

.brand-text {
  font-size: 1.55rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
  white-space: nowrap;
}

.main-nav {
  display: flex;
  justify-content: flex-end;
  flex-wrap: wrap;
  gap: 10px 14px;
  min-width: 0;
}

.nav-categories a {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  border-radius: 999px;
  color: #4f6d87;
  font-size: 1.04rem;
  font-weight: 600;
  line-height: 1.2;
  white-space: nowrap;
  transition: background 0.2s ease, color 0.2s ease, transform 0.18s ease;
}

.nav-categories a:hover {
  background: rgba(51, 169, 255, 0.10);
  color: var(--primary-dark);
  transform: translateY(-1px);
}

.nav-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--primary);
  flex: 0 0 auto;
}

.hero {
  padding: 42px 0 28px;
}

.hero-grid,
.feature-highlight,
.two-column-feature,
.section-grid,
.footer-grid {
  display: grid;
  gap: 34px;
}

.hero-grid,
.feature-highlight,
.two-column-feature {
  grid-template-columns: 1.15fr 0.85fr;
  align-items: center;
}

.section-grid,
.footer-grid {
  grid-template-columns: 0.8fr 1.2fr;
}

.eyebrow,
.section-label {
  margin-bottom: 12px;
  color: var(--primary-dark);
  font-size: 0.92rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

h1, h2, h3 {
  margin-top: 0;
  line-height: 1.15;
}

h1 {
  font-size: clamp(2.5rem, 5vw, 4.6rem);
  letter-spacing: -0.03em;
  margin-bottom: 18px;
}

h2 {
  font-size: clamp(2rem, 3vw, 3rem);
  letter-spacing: -0.03em;
  margin-bottom: 18px;
}

h3 {
  font-size: 1.25rem;
  margin-bottom: 12px;
}

.lead {
  font-size: 1.15rem;
  color: #24445c;
}

.hero-copy p,
.content-flow p,
.intro-block p,
.info-card p,
.topic-text,
.footer-grid p,
.site-footer p {
  color: var(--muted);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 28px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 12px 18px;
  border-radius: 999px;
  font-weight: 700;
  border: 1px solid transparent;
  transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
}

.button:hover,
.topic-card:hover,
.info-card:hover,
.card-panel:hover {
  transform: translateY(-2px);
}

.button-primary {
  background: linear-gradient(135deg, var(--primary), #8bd4ff);
  color: #fff;
  box-shadow: 0 18px 35px rgba(51, 169, 255, 0.25);
}

.button-secondary {
  background: rgba(255, 255, 255, 0.78);
  border-color: var(--line);
  color: var(--text);
}

.card-panel,
.info-card,
.topic-card {
  background: rgba(255, 255, 255, 0.86);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

.card-panel,
.info-card {
  border-radius: var(--radius-lg);
}

.hero-visual,
.product-card {
  overflow: hidden;
}

.hero-visual img,
.product-card img {
  aspect-ratio: 4 / 3;
  object-fit: cover;
}

.hero-note,
.product-meta {
  padding: 20px 22px 24px;
}

.hero-note {
  display: grid;
  gap: 8px;
}

.section {
  padding: 42px 0;
}

.alt-section {
  background: linear-gradient(180deg, rgba(231, 246, 255, 0.55) 0%, rgba(255, 255, 255, 0) 100%);
}

.bright-section {
  background: linear-gradient(180deg, rgba(212, 241, 255, 0.42) 0%, rgba(255, 255, 255, 0.25) 100%);
}

.intro-block {
  max-width: 760px;
  margin-bottom: 24px;
}

.intro-block.narrow {
  max-width: 680px;
}

.card-grid,
.topic-grid {
  display: grid;
  gap: 22px;
}

.three-up {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

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

.info-card {
  padding: 26px;
}

.soft-blue {
  background: rgba(243, 251, 255, 0.94);
}

.checklist-panel {
  padding: 28px;
}

.check-list {
  padding-left: 18px;
  margin-bottom: 0;
  color: var(--muted);
}

.check-list li + li {
  margin-top: 10px;
}

.check-list.compact li + li {
  margin-top: 8px;
}

.purchase-note {
  margin-top: 22px;
  max-width: 820px;
}

.topic-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.topic-card {
  display: grid;
  gap: 10px;
  padding: 24px;
  border-radius: var(--radius-md);
  transition: transform 0.18s ease, border-color 0.18s ease;
}

.topic-card:hover {
  border-color: rgba(20, 136, 222, 0.28);
}

.topic-title {
  font-size: 1.15rem;
  font-weight: 700;
}

.site-footer {
  padding: 34px 0 48px;
  border-top: 1px solid rgba(38, 125, 189, 0.08);
}

.footer-title {
  font-size: 1.35rem;
  margin-bottom: 10px;
}

.footer-nav {
  display: grid;
  gap: 10px;
  align-content: start;
}

@media (max-width: 1180px) {
  .header-inner {
    grid-template-columns: 1fr;
    gap: 18px;
  }

  .main-nav {
    justify-content: flex-start;
  }
}

@media (max-width: 1024px) {
  .hero-grid,
  .feature-highlight,
  .two-column-feature,
  .section-grid,
  .footer-grid,
  .three-up,
  .two-up,
  .topic-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .site-header {
    position: static;
  }

  .header-inner {
    min-height: auto;
    padding: 16px 0;
    gap: 14px;
  }

  .brand-logo {
    width: 46px;
    height: 46px;
  }

  .brand-text {
    font-size: 1.28rem;
    white-space: normal;
  }

  .main-nav {
    flex-direction: column;
    align-items: stretch;
    gap: 8px;
  }

  .nav-categories a {
    width: 100%;
    justify-content: flex-start;
    white-space: normal;
    padding: 12px 14px;
    background: rgba(255, 255, 255, 0.72);
    border: 1px solid var(--line);
  }

  .hero {
    padding-top: 24px;
  }

  h1 {
    font-size: 2.5rem;
  }

  h2 {
    font-size: 2rem;
  }

  .button,
  .topic-card,
  .info-card,
  .card-panel {
    width: 100%;
  }

  .hero-actions {
    flex-direction: column;
  }
}

/* Click-to-enlarge infographic / diagram image */
.zoom-figure {
  margin: 0;
}

.zoom-thumb-link {
  display: block;
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  cursor: zoom-in;
}

.product-card .zoom-thumb-link img,
.zoom-thumb-link img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  aspect-ratio: auto;
  object-fit: contain;
}

.zoom-thumb-hint {
  position: absolute;
  right: 14px;
  bottom: 14px;
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(21, 48, 71, 0.82);
  color: #ffffff;
  font-size: 0.9rem;
  font-weight: 700;
  line-height: 1;
  box-shadow: 0 10px 24px rgba(21, 48, 71, 0.18);
}

.image-lightbox {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: none;
  padding: 28px;
  background: rgba(10, 24, 36, 0.82);
  backdrop-filter: blur(4px);
}

.image-lightbox:target {
  display: flex;
  align-items: center;
  justify-content: center;
}

.image-lightbox-backdrop {
  position: absolute;
  inset: 0;
  display: block;
}

.image-lightbox-dialog {
  position: relative;
  z-index: 1;
  width: min(1100px, calc(100vw - 32px));
  max-height: calc(100vh - 32px);
  padding: 18px;
  border-radius: 24px;
  background: rgba(255, 255, 255, 0.98);
  box-shadow: 0 24px 70px rgba(10, 24, 36, 0.28);
  overflow: auto;
}

.image-lightbox-close {
  position: sticky;
  top: 0;
  margin-left: auto;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border-radius: 999px;
  background: #ffffff;
  color: var(--text);
  font-size: 1.5rem;
  font-weight: 700;
  line-height: 1;
  border: 1px solid var(--line);
  box-shadow: 0 10px 24px rgba(21, 48, 71, 0.12);
}

.image-lightbox-content {
  margin-top: 10px;
}

.image-lightbox-content img {
  display: block;
  width: 100%;
  height: auto;
  max-height: calc(100vh - 140px);
  max-width: 100%;
  aspect-ratio: auto;
  object-fit: contain;
  border-radius: 16px;
  background: #ffffff;
}

.image-lightbox-caption {
  margin: 14px 4px 0;
  color: var(--muted);
  font-size: 0.98rem;
}

@media (max-width: 720px) {
  .image-lightbox {
    padding: 14px;
  }

  .image-lightbox-dialog {
    width: calc(100vw - 16px);
    max-height: calc(100vh - 16px);
    padding: 12px;
    border-radius: 18px;
  }

  .zoom-thumb-hint {
    right: 10px;
    bottom: 10px;
    font-size: 0.82rem;
    padding: 7px 10px;
  }
}