/* ================================================================
   Qplus AI Tech 独立站 · 主样式（响应式大气 B2B 风）
   ================================================================ */
:root {
  --bg: #f4f6fb;
  --surface: #ffffff;
  --surface-2: #f8fafc;
  --border: #e4e8f0;
  --border-soft: #eef1f6;
  --text: #0f172a;
  --muted: #64748b;
  --muted-2: #94a3b8;
  --primary: #1d4ed8;
  --primary-hover: #1e40af;
  --primary-soft: #eff3ff;
  --accent: #2563eb;
  --radius: 10px;
  --radius-lg: 14px;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.05);
  --shadow: 0 4px 14px rgba(15, 23, 42, 0.06);
  --shadow-lg: 0 12px 32px rgba(15, 23, 42, 0.1);
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-head: 'Space Grotesk', 'Inter', sans-serif;
  --container: 1240px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

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

body {
  font-family: var(--font-body);
  color: var(--text);
  background: var(--bg);
  line-height: 1.55;
  font-size: 15px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }

/* ---------- 容器 ---------- */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 28px;
  width: 100%;
}

/* ============================================================
   1. 页头（响应式）
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
  z-index: 50;
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 24px;
  height: 68px;
}

.brand-mark {
  width: 32px; height: 32px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 700; font-family: var(--font-head);
}

.brand-name {
  font-family: var(--font-head);
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -.3px;
  line-height: 1;
}
.brand-tagline {
  font-size: .72rem;
  color: var(--muted);
  margin-top: 3px;
  line-height: 1;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.nav {
  display: flex;
  gap: 6px;
  align-items: center;
  flex: 1;
  justify-content: center;
}
.nav a {
  padding: 8px 14px;
  font-size: .92rem;
  color: var(--muted);
  border-radius: 8px;
  transition: all .18s;
  font-weight: 500;
}
.nav a:hover { color: var(--text); background: var(--surface-2); }
.nav a.active { color: var(--primary); background: var(--primary-soft); }

/* 品牌 tab 切换 */
.brand-tabs {
  display: flex;
  gap: 2px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 3px;
  flex-shrink: 0;
}
.brand-tab {
  padding: 6px 12px;
  font-size: .82rem;
  font-weight: 600;
  color: var(--muted);
  border-radius: 7px;
  transition: all .18s;
  white-space: nowrap;
}
.brand-tab:hover { color: var(--text); }
.brand-tab.active {
  background: #fff;
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

.header-right {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
  margin-left: auto;
}

.lang-btn {
  padding: 7px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: .85rem;
  font-weight: 600;
  color: var(--text);
  background: #fff;
  transition: all .18s;
}
.lang-btn:hover { border-color: var(--primary); color: var(--primary); }

/* 多语言分段控件 EN / 中 / RU */
.lang-switch {
  display: flex;
  gap: 2px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 3px;
  flex-shrink: 0;
}
.lang-opt {
  padding: 4px 9px;
  font-size: .78rem;
  font-weight: 600;
  color: var(--muted);
  border-radius: 6px;
  transition: all .18s;
  white-space: nowrap;
}
.lang-opt:hover { color: var(--text); }
.lang-opt.active {
  background: #fff;
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

.menu-btn {
  display: none;
  font-size: 1.4rem;
  padding: 4px 8px;
  color: var(--text);
}

/* 窄屏响应：折叠 nav + brand-tabs */
@media (max-width: 1024px) {
  .container { padding: 0 20px; }
  .nav { display: none; }
  .brand-tabs { margin-left: auto; }
}
@media (max-width: 720px) {
  .header-inner { height: 60px; gap: 12px; }
  .brand-tab { padding: 5px 9px; font-size: .76rem; }
  .lang-opt { padding: 4px 8px; font-size: .74rem; }
  .brand-tagline { display: none; }
}

/* ============================================================
   2. Hero
   ============================================================ */
.hero {
  background: linear-gradient(180deg, #eef3fc 0%, var(--bg) 100%);
  padding: 80px 0 70px;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -100px; right: -100px;
  width: 500px; height: 500px;
  background: radial-gradient(circle, rgba(29, 78, 216, 0.12), transparent 70%);
  pointer-events: none;
}

.hero-inner {
  text-align: center;
  position: relative;
  z-index: 1;
  max-width: 880px;
  margin: 0 auto;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(29, 78, 216, 0.08);
  color: var(--primary);
  padding: 7px 16px;
  border-radius: 100px;
  font-size: .82rem;
  font-weight: 600;
  letter-spacing: .5px;
  margin-bottom: 24px;
  border: 1px solid rgba(29, 78, 216, 0.15);
}
.hero-eyebrow-dot {
  width: 7px; height: 7px;
  background: var(--primary);
  border-radius: 50%;
}

.hero h1 {
  font-family: var(--font-head);
  font-weight: 700;
  letter-spacing: -1.2px;
  line-height: 1.08;
  margin-bottom: 22px;
  /* 关键：响应式字号 */
  font-size: clamp(2.4rem, 5.5vw, 4.2rem);
  color: var(--text);
}
.hero h1 em {
  font-style: normal;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  font-weight: 700;
}

.hero-lead {
  font-size: clamp(1rem, 1.4vw, 1.15rem);
  color: var(--muted);
  margin-bottom: 36px;
  max-width: 720px;
  margin-left: auto;
  margin-right: auto;
}

.hero-actions {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 36px;
}

.hero-badges {
  display: flex;
  gap: 28px;
  justify-content: center;
  flex-wrap: wrap;
  font-size: .88rem;
  color: var(--muted);
}
.hero-badges span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.hero-badges span::before {
  content: '✓';
  color: #10b981;
  font-weight: 700;
}

@media (max-width: 720px) {
  .hero { padding: 56px 0 50px; }
  .hero-actions { flex-direction: column; align-items: stretch; }
  .hero-badges { gap: 14px; font-size: .82rem; }
}

/* ============================================================
   3. 按钮
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 22px;
  border-radius: 10px;
  font-size: .95rem;
  font-weight: 600;
  transition: all .18s;
  cursor: pointer;
  white-space: nowrap;
  line-height: 1;
}
.btn-lg { padding: 14px 28px; font-size: 1rem; }

.btn-primary {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 4px 14px rgba(29, 78, 216, 0.3);
}
.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(29, 78, 216, 0.4);
}

.btn-ghost {
  background: #fff;
  color: var(--text);
  border: 1.5px solid var(--border);
}
.btn-ghost:hover {
  border-color: var(--primary);
  color: var(--primary);
}

/* ============================================================
   4. Stats 条
   ============================================================ */
.stats-bar {
  background: #fff;
  border-top: 1px solid var(--border-soft);
  border-bottom: 1px solid var(--border-soft);
  padding: 28px 0;
}
.stats-inner {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 28px;
  text-align: center;
}
.stat-item {
  padding: 0 10px;
  border-right: 1px solid var(--border-soft);
}
.stat-item:last-child { border-right: none; }
.stat-num {
  font-family: var(--font-head);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--primary);
  letter-spacing: -.5px;
  line-height: 1.2;
}
.stat-label {
  font-size: .82rem;
  color: var(--muted);
  margin-top: 4px;
}
@media (max-width: 720px) {
  .stats-inner { grid-template-columns: repeat(2, 1fr); gap: 20px; }
  .stat-item { border-right: none; padding: 0; }
  .stat-item:nth-child(odd) { border-right: 1px solid var(--border-soft); }
}

/* ============================================================
   5. 通用 section / 标题
   ============================================================ */
.section {
  padding: 72px 0;
}
.section-alt {
  background: #fff;
  border-top: 1px solid var(--border-soft);
  border-bottom: 1px solid var(--border-soft);
}

.section-head {
  margin-bottom: 42px;
  max-width: 720px;
}
.section-head-center {
  text-align: center;
  margin-left: auto;
  margin-right: auto;
}
.section-title {
  font-family: var(--font-head);
  font-size: clamp(1.7rem, 2.5vw, 2.2rem);
  font-weight: 700;
  letter-spacing: -.8px;
  margin-bottom: 12px;
  line-height: 1.15;
}
.section-sub {
  color: var(--muted);
  font-size: 1rem;
}

/* ============================================================
   6. Grid
   ============================================================ */
.grid { display: grid; gap: 22px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 720px) {
  .section { padding: 52px 0; }
  .grid-3 { grid-template-columns: 1fr; }
}

/* ============================================================
   7. 分类卡片
   ============================================================ */
.cat-card {
  background: #fff;
  border: 1.5px solid var(--border-soft);
  border-radius: var(--radius-lg);
  padding: 30px;
  transition: all .25s;
  display: block;
  position: relative;
  overflow: hidden;
}
.cat-card:hover {
  border-color: var(--primary);
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}
.cat-icon {
  width: 52px; height: 52px;
  background: var(--primary-soft);
  color: var(--primary);
  border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 20px;
}
.cat-card h3 {
  font-family: var(--font-head);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 8px;
}
.cat-card p {
  color: var(--muted);
  font-size: .92rem;
  margin-bottom: 18px;
}
.cat-card-link {
  color: var(--primary);
  font-weight: 600;
  font-size: .9rem;
}

/* ============================================================
   8. 产品卡
   ============================================================ */
.product-card {
  background: #fff;
  border: 1.5px solid var(--border-soft);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: all .25s;
  display: flex;
  flex-direction: column;
}
.product-card:hover {
  border-color: var(--primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}
.product-card-thumb {
  height: 120px;
  background: linear-gradient(135deg, var(--primary-soft), #f8fafc);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.6rem;
  color: var(--primary);
  margin-bottom: 18px;
  font-weight: 700;
}
.product-card-brand {
  font-size: .72rem;
  font-weight: 600;
  color: var(--muted-2);
  letter-spacing: 1px;
  text-transform: uppercase;
}
.product-card-name {
  font-family: var(--font-head);
  font-size: 1.05rem;
  font-weight: 700;
  margin: 6px 0 8px;
  letter-spacing: -.3px;
}
.product-card-specs {
  color: var(--muted);
  font-size: .85rem;
  flex: 1;
  margin-bottom: 18px;
}
.product-card-foot {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 14px;
  border-top: 1px solid var(--border-soft);
}
.product-card-price {
  font-weight: 700;
  color: var(--text);
  font-size: .92rem;
}
.product-card-cta {
  color: var(--primary);
  font-weight: 600;
  font-size: .88rem;
}

/* ============================================================
   9. 筛选 chips
   ============================================================ */
.chips {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin: 30px 0 8px;
}
.chip {
  padding: 8px 16px;
  background: #fff;
  border: 1.5px solid var(--border);
  border-radius: 100px;
  font-size: .88rem;
  font-weight: 600;
  color: var(--muted);
  transition: all .18s;
}
.chip:hover { color: var(--text); border-color: var(--text); }
.chip.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

/* ============================================================
   10. 分组小标题（产品页）
   ============================================================ */
.cat-group-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin: 36px 0 18px;
}
.cat-group-head h2 {
  font-family: var(--font-head);
  font-size: 1.4rem;
  font-weight: 700;
}
.cat-group-head .count {
  color: var(--muted);
  font-size: .88rem;
}
.cat-group-head:first-of-type { margin-top: 12px; }

/* ============================================================
   11. 详情页
   ============================================================ */
.detail-wrap {
  padding: 48px 0 80px;
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 48px;
}
@media (max-width: 900px) {
  .detail-wrap { grid-template-columns: 1fr; gap: 28px; }
}
.detail-img {
  height: 360px;
  background: linear-gradient(135deg, var(--primary-soft), #f8fafc);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 5rem;
  color: var(--primary);
}
.detail-back {
  display: inline-block;
  margin: 32px 0 14px;
  color: var(--muted);
  font-size: .9rem;
  font-weight: 500;
}
.detail-back:hover { color: var(--primary); }
.detail-brand {
  font-size: .78rem;
  font-weight: 600;
  color: var(--muted-2);
  letter-spacing: 1.5px;
  text-transform: uppercase;
  margin-bottom: 6px;
}
.detail-name {
  font-family: var(--font-head);
  font-size: clamp(1.8rem, 3vw, 2.4rem);
  font-weight: 700;
  letter-spacing: -.6px;
  margin-bottom: 14px;
}
.detail-desc {
  color: var(--muted);
  margin-bottom: 24px;
  font-size: 1rem;
  line-height: 1.65;
}
.detail-specs {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 24px;
  border: 1px solid var(--border-soft);
}
.detail-specs h4 {
  font-size: .82rem;
  font-weight: 700;
  letter-spacing: 1px;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 14px;
}
.detail-specs table {
  width: 100%;
  font-size: .9rem;
}
.detail-specs td {
  padding: 7px 0;
  border-bottom: 1px dashed var(--border);
}
.detail-specs td:first-child {
  color: var(--muted);
  width: 40%;
}
.detail-specs tr:last-child td { border-bottom: none; }

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

/* ============================================================
   12. Why us 卡
   ============================================================ */
.feature-card {
  background: #fff;
  padding: 28px 24px;
  border-radius: var(--radius-lg);
  border: 1.5px solid var(--border-soft);
}
.feature-icon {
  font-size: 1.8rem;
  margin-bottom: 14px;
}
.feature-card h4 {
  font-family: var(--font-head);
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 8px;
}
.feature-card p {
  color: var(--muted);
  font-size: .9rem;
  line-height: 1.6;
}

/* ============================================================
   13. CTA Band
   ============================================================ */
.cta-band {
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
  color: #fff;
  padding: 56px 0;
}
.cta-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 28px;
  flex-wrap: wrap;
}
.cta-inner h2 { color: #fff; margin-bottom: 6px; }
.cta-inner p { color: #cbd5e1; }
@media (max-width: 720px) {
  .cta-inner { flex-direction: column; text-align: center; }
}

/* ============================================================
   14. About 页
   ============================================================ */
.page-head {
  background: linear-gradient(180deg, #eef3fc 0%, var(--bg) 100%);
  padding: 60px 0 40px;
  text-align: center;
  border-bottom: 1px solid var(--border-soft);
}
.page-head h1 {
  font-family: var(--font-head);
  font-size: clamp(2rem, 4vw, 2.8rem);
  font-weight: 700;
  letter-spacing: -.8px;
  margin-bottom: 12px;
}
.page-head p { color: var(--muted); max-width: 640px; margin: 0 auto; }

.prose {
  max-width: 760px;
  margin: 0 auto;
  font-size: 1.02rem;
  line-height: 1.75;
}
.prose p { margin-bottom: 18px; color: #334155; }
.prose h2 {
  font-family: var(--font-head);
  font-size: 1.4rem;
  font-weight: 700;
  margin: 36px 0 16px;
}
.prose ul {
  list-style: none;
  padding: 0;
}
.prose li {
  padding: 10px 0 10px 28px;
  position: relative;
  color: #334155;
}
.prose li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--primary);
  font-weight: 700;
}

.process-step {
  display: flex;
  gap: 18px;
  padding: 18px 0;
  border-bottom: 1px solid var(--border-soft);
}
.step-num {
  flex-shrink: 0;
  width: 38px; height: 38px;
  background: var(--primary);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-family: var(--font-head);
}
.step-content h4 {
  font-size: 1rem;
  font-weight: 600;
}

/* ============================================================
   15. Contact 页
   ============================================================ */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 48px;
  padding: 48px 0 80px;
}
@media (max-width: 900px) {
  .contact-grid { grid-template-columns: 1fr; gap: 28px; }
}

.contact-info-card {
  background: #fff;
  padding: 28px;
  border-radius: var(--radius-lg);
  border: 1.5px solid var(--border-soft);
  margin-bottom: 14px;
}
.contact-info-row {
  display: flex;
  gap: 14px;
  padding: 12px 0;
  border-bottom: 1px solid var(--border-soft);
  align-items: center;
}
.contact-info-row:last-child { border-bottom: none; }
.contact-info-label {
  font-size: .78rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  font-weight: 600;
  min-width: 90px;
}
.contact-info-value {
  color: var(--text);
  font-weight: 500;
  word-break: break-all;
}
.contact-info-value a:hover { color: var(--primary); }

.form-card {
  background: #fff;
  padding: 32px;
  border-radius: var(--radius-lg);
  border: 1.5px solid var(--border-soft);
  box-shadow: var(--shadow-sm);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}
@media (max-width: 600px) {
  .form-row { grid-template-columns: 1fr; }
}

.field { margin-bottom: 16px; }
.field label {
  display: block;
  font-size: .82rem;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--text);
}
.field input, .field textarea {
  width: 100%;
  padding: 11px 14px;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  font-size: .95rem;
  font-family: inherit;
  color: var(--text);
  background: var(--surface-2);
  transition: all .15s;
}
.field input:focus, .field textarea:focus {
  outline: none;
  border-color: var(--primary);
  background: #fff;
  box-shadow: 0 0 0 3px rgba(29, 78, 216, 0.1);
}
.field textarea {
  resize: vertical;
  min-height: 110px;
}

.form-note {
  font-size: .8rem;
  color: var(--muted);
  margin-top: 12px;
  text-align: center;
}
.form-status {
  margin-top: 12px;
  padding: 10px 14px;
  border-radius: 8px;
  font-size: .9rem;
  display: none;
}
.form-status.show { display: block; }
.form-status.ok {
  background: #ecfdf5;
  color: #065f46;
  border: 1px solid #a7f3d0;
}
.form-status.err {
  background: #fef2f2;
  color: #991b1b;
  border: 1px solid #fecaca;
}

/* ============================================================
   16. 页脚
   ============================================================ */
.site-footer {
  background: #fff;
  border-top: 1px solid var(--border);
  padding: 36px 0 28px;
  margin-top: 60px;
}
.footer-inner { max-width: var(--container); margin: 0 auto; padding: 0 28px; }
.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 18px;
  margin-bottom: 22px;
}
.footer-brand { display: flex; flex-direction: column; gap: 4px; }
.footer-links {
  display: flex;
  gap: 22px;
}
.footer-links a {
  color: var(--muted);
  font-size: .9rem;
}
.footer-links a:hover { color: var(--primary); }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  padding-top: 18px;
  border-top: 1px solid var(--border-soft);
  font-size: .85rem;
  color: var(--muted);
  flex-wrap: wrap;
  gap: 8px;
}
.muted { color: var(--muted); }

/* 页脚社媒 */
.footer-social {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
  padding: 18px 0 4px;
  margin-top: 4px;
  border-top: 1px solid var(--border-soft);
}
.footer-social-label { font-size: .82rem; color: var(--muted); font-weight: 600; }
.social-links { display: flex; gap: 10px; }
.social-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px; height: 34px;
  border-radius: 9px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text);
  transition: all .18s;
}
.social-link:hover { color: #fff; transform: translateY(-2px); }
.social-link.social-linkedin:hover  { background: #0a66c2; border-color: #0a66c2; }
.social-link.social-tiktok:hover    { background: #000;    border-color: #000;    }
.social-link.social-telegram:hover  { background: #229ed9; border-color: #229ed9; }
.social-link.social-facebook:hover  { background: #1877f2; border-color: #1877f2; }
.social-link.social-pinterest:hover { background: #bd081c; border-color: #bd081c; }
.social-link.social-whatsapp:hover  { background: #25d366; border-color: #25d366; }