/* ===== Variables ===== */
:root {
  --color-bg: #fafbfc;
  --color-bg-alt: #f0f4f8;
  --color-white: #ffffff;
  --color-text: #2d3748;
  --color-text-light: #718096;
  --color-primary: #5ba4c9;
  --color-primary-dark: #4a8fb0;
  --color-accent: #e8637a;
  --color-border: #e2e8f0;
  --color-shadow: rgba(45, 55, 72, 0.08);
  --font-en: 'DM Sans', system-ui, sans-serif;
  --font-zh: 'Noto Sans SC', 'DM Sans', system-ui, sans-serif;
  --radius: 12px;
  --radius-lg: 20px;
  --header-h: 76px;
  --transition: 0.25s ease;
}

/* ===== Reset ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-h);
}

body {
  font-family: var(--font-en);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

body.lang-zh { font-family: var(--font-zh); }

img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }

.container {
  width: min(1120px, 92vw);
  margin: 0 auto;
}

/* ===== Header ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-h);
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow var(--transition);
}

.header.scrolled { box-shadow: 0 2px 20px var(--color-shadow); }

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  gap: 2rem;
}

.logo {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}

.logo__img {
  height: 40px;
  width: auto;
  max-width: min(220px, 40vw);
  display: block;
  object-fit: contain;
}

.logo__img--footer {
  height: 30px;
  max-width: 180px;
  filter: brightness(0) invert(1);
  opacity: 0.95;
}

.logo__mark {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, var(--color-primary), #7ec8e8);
  color: white;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 700;
}

.logo__mark--sm { width: 28px; height: 28px; font-size: 0.85rem; border-radius: 8px; }

.nav {
  display: flex;
  gap: 2rem;
}

.nav a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-light);
  transition: color var(--transition);
  position: relative;
}

.nav a:hover,
.nav a.active { color: var(--color-primary); }

.nav a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-primary);
  border-radius: 1px;
}

.header__actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.lang-toggle {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  background: var(--color-white);
  cursor: pointer;
  font-size: 0.8rem;
  font-weight: 600;
  transition: border-color var(--transition), background var(--transition);
}

.lang-toggle:hover { border-color: var(--color-primary); }

.lang-toggle__active { color: var(--color-primary); }
.lang-toggle__inactive { color: var(--color-text-light); }
.lang-toggle__sep { color: var(--color-border); }

body.lang-zh .lang-toggle__active { color: var(--color-text-light); }
body.lang-zh .lang-toggle__inactive { color: var(--color-primary); }

.menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 0.5rem;
  border: none;
  background: none;
  cursor: pointer;
}

.menu-btn span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: 1px;
  transition: var(--transition);
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.75rem;
  border-radius: 999px;
  font-size: 0.95rem;
  font-weight: 600;
  transition: all var(--transition);
  cursor: pointer;
  border: 2px solid transparent;
}

.btn--primary {
  background: var(--color-primary);
  color: white;
}

.btn--primary:hover {
  background: var(--color-primary-dark);
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(91, 164, 201, 0.35);
}

.btn--outline {
  background: transparent;
  border-color: var(--color-border);
  color: var(--color-text);
}

.btn--outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.btn--full { width: 100%; }

/* ===== Hero ===== */
.hero {
  padding: calc(var(--header-h) + 4rem) 0 5rem;
  background: linear-gradient(180deg, #eef6fb 0%, var(--color-bg) 100%);
  overflow: hidden;
}

.hero__inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.hero__tag {
  display: inline-block;
  padding: 0.35rem 1rem;
  background: rgba(91, 164, 201, 0.12);
  color: var(--color-primary);
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 1.25rem;
}

.hero__title {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1.25rem;
  letter-spacing: -0.02em;
}

.hero__desc {
  color: var(--color-text-light);
  font-size: 1.05rem;
  max-width: 520px;
  margin-bottom: 2rem;
}

.hero__actions {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 2.5rem;
}

.hero__stats {
  display: flex;
  gap: 2.5rem;
}

.stat strong {
  display: block;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary);
}

.stat span {
  font-size: 0.85rem;
  color: var(--color-text-light);
}

.hero__visual {
  position: relative;
  display: flex;
  justify-content: center;
}

.hero__img-wrap {
  background: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: 0 20px 60px var(--color-shadow);
}

.hero__img-wrap img {
  max-height: 480px;
  object-fit: contain;
  margin: 0 auto;
}

.hero__badge {
  position: absolute;
  bottom: 1rem;
  left: 0;
  background: var(--color-white);
  padding: 0.6rem 1.25rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
  box-shadow: 0 4px 16px var(--color-shadow);
  color: var(--color-accent);
}

/* ===== Sections ===== */
.section {
  padding: 5rem 0;
}

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

.section__head {
  text-align: center;
  max-width: 640px;
  margin: 0 auto 3.5rem;
}

.section__label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 0.75rem;
}

.section__title {
  font-size: clamp(1.75rem, 3vw, 2.25rem);
  font-weight: 700;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}

.section__desc {
  color: var(--color-text-light);
  font-size: 1.05rem;
}

/* ===== Products ===== */
.product-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.5rem;
}

.product-card {
  background: var(--color-white);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: 0 2px 12px var(--color-shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}

.product-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 30px var(--color-shadow);
}

.product-card__img {
  aspect-ratio: 3/4;
  background: #f8fafc;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
}

.product-card__img img {
  max-height: 100%;
  object-fit: contain;
}

.product-card__info {
  padding: 1.25rem 1.5rem 1.5rem;
}

.product-card__info h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.35rem;
}

.product-card__info p {
  font-size: 0.875rem;
  color: var(--color-text-light);
}

/* ===== Features ===== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3.5rem;
}

.feature-card {
  background: var(--color-white);
  padding: 2rem;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  transition: border-color var(--transition);
}

.feature-card:hover { border-color: var(--color-primary); }

.feature-card__icon {
  font-size: 1.75rem;
  margin-bottom: 1rem;
}

.feature-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.feature-card p {
  font-size: 0.9rem;
  color: var(--color-text-light);
}

.specs-table-wrap {
  background: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 2rem;
  border: 1px solid var(--color-border);
}

.specs-table__title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 1.25rem;
}

.specs-table {
  width: 100%;
  border-collapse: collapse;
}

.specs-table th,
.specs-table td {
  padding: 0.85rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.95rem;
}

.specs-table th {
  font-weight: 600;
  width: 35%;
  color: var(--color-text);
}

.specs-table td { color: var(--color-text-light); }

.specs-table tr:last-child th,
.specs-table tr:last-child td { border-bottom: none; }

/* ===== Customization ===== */
.custom-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.custom-list {
  margin: 1.5rem 0 2rem;
}

.custom-list li {
  padding: 0.6rem 0 0.6rem 1.75rem;
  position: relative;
  color: var(--color-text-light);
  font-size: 0.95rem;
}

.custom-list li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--color-primary);
  font-weight: 700;
}

.custom-layout__visual {
  position: relative;
}

.custom-layout__visual img {
  border-radius: var(--radius-lg);
  box-shadow: 0 16px 48px var(--color-shadow);
}

.custom-layout__card {
  position: absolute;
  bottom: -1.5rem;
  left: -1.5rem;
  background: var(--color-white);
  padding: 1.25rem 1.75rem;
  border-radius: var(--radius);
  box-shadow: 0 8px 30px var(--color-shadow);
}

.custom-layout__card p {
  font-size: 0.8rem;
  color: var(--color-text-light);
  margin-bottom: 0.25rem;
}

.custom-layout__card strong {
  display: block;
  font-size: 1.5rem;
  color: var(--color-primary);
}

.custom-layout__card span {
  font-size: 0.85rem;
  color: var(--color-text-light);
}

/* ===== About ===== */
.about-layout {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 4rem;
  align-items: center;
}

.about-layout__visual img {
  border-radius: var(--radius-lg);
  box-shadow: 0 16px 48px var(--color-shadow);
}

.about-layout__text p {
  color: var(--color-text-light);
  margin-bottom: 1rem;
  font-size: 0.95rem;
}

.about-highlights {
  display: flex;
  gap: 2.5rem;
  margin-top: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--color-border);
}

.about-highlight strong {
  display: block;
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--color-primary);
}

.about-highlight span {
  font-size: 0.85rem;
  color: var(--color-text-light);
}

/* ===== Contact ===== */
.contact-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: start;
}

.contact-details {
  margin-top: 2rem;
}

.contact-item {
  padding: 1rem 0;
  border-bottom: 1px solid var(--color-border);
}

.contact-item__label {
  display: block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-light);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.25rem;
}

.contact-item a {
  color: var(--color-primary);
  font-weight: 500;
}

.contact-item a:hover { text-decoration: underline; }

.contact-form {
  background: var(--color-white);
  padding: 2rem;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
}

.form-group {
  margin-bottom: 1.25rem;
}

.form-group label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 0.4rem;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 0.95rem;
  transition: border-color var(--transition);
  background: var(--color-bg);
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  background: var(--color-white);
}

.form-group textarea { resize: vertical; min-height: 100px; }

.form-note {
  text-align: center;
  font-size: 0.8rem;
  color: var(--color-text-light);
  margin-top: 0.75rem;
}

/* ===== Footer ===== */
.footer {
  padding: 2rem 0;
  background: var(--color-text);
  color: rgba(255, 255, 255, 0.7);
}

.footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer__brand {
  display: flex;
  align-items: center;
}

.footer__copy { font-size: 0.85rem; }

.footer__top {
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.6);
  transition: color var(--transition);
}

.footer__top:hover { color: white; }

/* ===== Mobile Nav ===== */
@media (max-width: 900px) {
  .nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    background: var(--color-white);
    flex-direction: column;
    padding: 1.5rem 2rem;
    gap: 0;
    border-bottom: 1px solid var(--color-border);
    transform: translateY(-120%);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--transition), opacity var(--transition);
  }

  .nav.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav a {
    padding: 0.85rem 0;
    border-bottom: 1px solid var(--color-border);
  }

  .nav a:last-child { border-bottom: none; }

  .menu-btn { display: flex; }

  .menu-btn.open span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
  .menu-btn.open span:nth-child(2) { opacity: 0; }
  .menu-btn.open span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

  .hero__inner,
  .custom-layout,
  .about-layout,
  .contact-layout {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .hero__visual { order: -1; }

  .hero__img-wrap img { max-height: 320px; }

  .hero__stats { gap: 1.5rem; }

  .about-layout__visual { order: -1; }

  .custom-layout__card {
    left: auto;
    right: 0;
    bottom: -1rem;
  }
}

@media (max-width: 480px) {
  .hero { padding-top: calc(var(--header-h) + 2rem); }
  .section { padding: 3.5rem 0; }
  .hero__actions { flex-direction: column; }
  .hero__actions .btn { width: 100%; }
  .about-highlights { flex-direction: column; gap: 1rem; }
}