/* ==========================================================================
   豹得快·钢贸通 官网样式库 (style.css)
   设计基调：明亮科技蓝白风、纯净通透、呼应官方 #008FD7 品牌天青蓝
   ========================================================================== */

:root {
  /* 官方品牌核心色 (呼应豹得快 LOGO #008FD7) */
  --brand-primary: #008FD7;
  --brand-hover: #0077B6;
  --brand-active: #006296;
  --brand-light: #F0F8FD;
  --brand-tint: #E1F1FB;
  --brand-glow: rgba(0, 143, 215, 0.2);
  --brand-gradient: linear-gradient(135deg, #008FD7 0%, #00B4D8 100%);
  --brand-gradient-hover: linear-gradient(135deg, #0077B6 0%, #0096C7 100%);

  /* 明亮通透背景色体系 */
  --bg-page: #FFFFFF;
  --bg-surface: #FFFFFF;
  --bg-muted: #F8FAFC;
  --bg-card: #FFFFFF;
  --bg-highlight: #F0F8FD;

  /* 边框与阴影系统 */
  --border-light: #E2E8F0;
  --border-subtle: #EDF2F7;
  --border-brand: rgba(0, 143, 215, 0.22);
  --border-focus: #008FD7;

  --shadow-xs: 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-sm: 0 2px 4px rgba(15, 23, 42, 0.05);
  --shadow-card: 0 10px 30px -5px rgba(0, 143, 215, 0.08), 0 4px 10px -2px rgba(15, 23, 42, 0.03);
  --shadow-glow: 0 12px 36px rgba(0, 143, 215, 0.12);
  --shadow-card-hover: 0 16px 36px -4px rgba(0, 143, 215, 0.14), 0 6px 12px -2px rgba(15, 23, 42, 0.05);

  /* 文字对比度系统 (高辨识度与阅读舒适感) */
  --text-main: #0F172A;
  --text-body: #334155;
  --text-muted: #64748B;
  --text-dim: #94A3B8;
  --text-inverse: #FFFFFF;

  /* 业务状态高显色 */
  --accent-gold: #B45309;
  --accent-gold-bg: #FEF3C7;
  --accent-emerald: #059669;
  --accent-emerald-bg: #DCFCE7;
  --accent-rose: #DC2626;
  --accent-rose-bg: #FEE2E2;

  /* 几何尺寸与圆角规范 */
  --radius-xs: 6px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --container-max: 1200px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

/* 全局重置 */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-family: var(--font-sans);
  background-color: var(--bg-page);
  color: var(--text-main);
  line-height: 1.6;
}

body {
  overflow-x: hidden;
  background-color: var(--bg-page);
  background-image:
    radial-gradient(circle at 10% 8%, rgba(0, 143, 215, 0.07) 0%, transparent 45%),
    radial-gradient(circle at 90% 35%, rgba(0, 180, 216, 0.05) 0%, transparent 40%),
    linear-gradient(to bottom, #FFFFFF 0%, #F8FAFC 100%);
  min-height: 100vh;
}

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

.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

/* 按钮通用规范 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  border-radius: var(--radius-full);
  padding: 10px 22px;
  font-size: 14px;
  transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  cursor: pointer;
  border: 1px solid transparent;
  white-space: nowrap;
}

.btn-primary {
  background: var(--brand-gradient);
  color: var(--text-inverse);
  box-shadow: 0 4px 14px rgba(0, 143, 215, 0.32);
}

.btn-primary:hover {
  background: var(--brand-gradient-hover);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 143, 215, 0.45);
}

.btn-secondary {
  background: var(--brand-light);
  color: var(--brand-primary);
  border: 1px solid var(--border-brand);
}

.btn-secondary:hover {
  background: var(--brand-tint);
  border-color: var(--brand-primary);
  transform: translateY(-2px);
}

.btn-large {
  padding: 14px 32px;
  font-size: 16px;
  font-weight: 700;
}

/* ==========================================================================
   1. 顶部导航栏 (Navbar)
   ========================================================================== */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--border-light);
  height: 72px;
  box-shadow: 0 2px 10px rgba(15, 23, 42, 0.03);
}

.nav-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.logo-group {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  user-select: none;
}

.logo-img {
  height: 34px;
  width: auto;
  max-width: 80px;
  object-fit: contain;
  display: block;
  transition: transform 0.25s ease;
}

.logo-group:hover .logo-img {
  transform: scale(1.05);
}

.logo-text-wrap {
  display: flex;
  align-items: baseline;
}

.logo-text {
  font-size: 20px;
  font-weight: 800;
  letter-spacing: -0.5px;
  color: var(--text-main);
}

.logo-sub {
  font-size: 14px;
  font-weight: 600;
  color: var(--brand-primary);
  margin-left: 4px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-links a.nav-item {
  font-size: 14px;
  color: var(--text-muted);
  transition: color 0.2s ease;
  font-weight: 500;
}

.nav-links a.nav-item:hover {
  color: var(--brand-primary);
}

/* ==========================================================================
   2. 主视觉区 (Hero Section)
   ========================================================================== */
.hero {
  padding: 80px 0 60px;
  text-align: center;
  position: relative;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 18px;
  border-radius: var(--radius-full);
  background: var(--brand-light);
  border: 1px solid var(--border-brand);
  color: var(--brand-primary);
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 24px;
  box-shadow: 0 2px 6px rgba(0, 143, 215, 0.08);
}

.hero-title {
  font-size: 48px;
  font-weight: 900;
  line-height: 1.25;
  letter-spacing: -0.8px;
  margin-bottom: 20px;
  color: var(--text-main);
}

.hero-title .gradient-text {
  background: linear-gradient(135deg, #008FD7 0%, #0284C7 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 18px;
  color: var(--text-muted);
  max-width: 700px;
  margin: 0 auto 36px;
  line-height: 1.6;
}

.hero-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  max-width: 960px;
  margin: 64px auto 0;
  padding: 24px;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
}

.stat-item {
  text-align: center;
}

.stat-num {
  font-size: 28px;
  font-weight: 800;
  color: var(--brand-primary);
  font-family: var(--font-mono);
}

.stat-desc {
  font-size: 13px;
  color: var(--text-muted);
  margin-top: 4px;
}

/* ==========================================================================
   3. 核心交互区：免登录在线不锈钢理算器 (Calculator Section)
   ========================================================================== */
.calc-section {
  padding: 80px 0;
}

.section-header {
  text-align: center;
  max-width: 650px;
  margin: 0 auto 40px;
}

.section-tag {
  color: var(--brand-primary);
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.section-title {
  font-size: 32px;
  font-weight: 800;
  margin-top: 8px;
  letter-spacing: -0.5px;
  color: var(--text-main);
}

.section-desc {
  color: var(--text-muted);
  font-size: 15px;
  margin-top: 8px;
}

.calc-container {
  max-width: 980px;
  margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border-brand);
  box-shadow: var(--shadow-glow), var(--shadow-card);
  border-radius: var(--radius-lg);
  padding: 36px;
  position: relative;
  overflow: hidden;
}

.calc-container::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--brand-gradient);
}

.calc-panel {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

.calc-row-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 10px;
}

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

.tab-pill {
  background: var(--bg-muted);
  border: 1px solid var(--border-light);
  color: var(--text-body);
  padding: 8px 18px;
  border-radius: var(--radius-full);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}

.tab-pill:hover {
  background: var(--brand-light);
  border-color: var(--brand-primary);
  color: var(--brand-primary);
}

.tab-pill.active {
  background: var(--brand-primary);
  border-color: var(--brand-primary);
  color: var(--text-inverse);
  box-shadow: 0 4px 12px rgba(0, 143, 215, 0.3);
}

.custom-density-wrap {
  margin-top: 10px;
}

.custom-density-input {
  background: var(--bg-surface);
  border: 1px solid var(--border-brand);
  color: var(--text-main);
  padding: 8px 14px;
  border-radius: var(--radius-xs);
  font-size: 14px;
  width: 240px;
  font-family: var(--font-mono);
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.custom-density-input:focus {
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 3px rgba(0, 143, 215, 0.15);
}

.input-grid-4 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
  margin-top: 8px;
}

.calc-input-box {
  background: var(--bg-muted);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  transition: all 0.2s ease;
}

.calc-input-box:focus-within {
  background: var(--bg-surface);
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 3px rgba(0, 143, 215, 0.15);
}

.calc-input-box label {
  font-size: 12px;
  color: var(--text-muted);
  font-weight: 600;
}

.calc-input-box input,
.calc-input-box select {
  background: transparent;
  border: none;
  outline: none;
  color: var(--text-main);
  font-size: 18px;
  font-weight: 700;
  font-family: var(--font-mono);
  width: 100%;
}

/* 结果仪表盘 */
.calc-result-board {
  background: linear-gradient(135deg, #F0F8FD 0%, #E6F3FA 100%);
  border: 1px solid var(--border-brand);
  border-radius: var(--radius-md);
  padding: 24px;
  margin-top: 12px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 20px;
  box-shadow: inset 0 1px 3px rgba(0, 143, 215, 0.05);
}

.result-card {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.result-card .r-title {
  font-size: 13px;
  color: var(--text-muted);
  font-weight: 500;
}

.result-card .r-value {
  font-size: 28px;
  font-weight: 800;
  font-family: var(--font-mono);
  color: var(--text-main);
}

.result-card .r-value small {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-muted);
  margin-left: 4px;
}

.result-card.highlight .r-value {
  color: var(--brand-primary);
}

.result-card.gold {
  grid-column: 1 / -1;
  border-top: 1px dashed var(--border-brand);
  padding-top: 16px;
}

.result-card.gold .r-title {
  color: var(--accent-gold);
  font-weight: 600;
}

.result-card.gold .r-value {
  color: var(--accent-gold);
  font-size: 34px;
}

/* 转化触发展示条 */
.calc-cta-bar {
  margin-top: 24px;
  padding: 20px 24px;
  background: var(--brand-light);
  border: 1px dashed var(--border-brand);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

.calc-cta-info {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.calc-cta-info strong {
  font-size: 15px;
  color: var(--text-main);
}

.calc-cta-info span {
  font-size: 13px;
  color: var(--text-muted);
}

/* 专供 SEO 与 AI 抓取的公式百科卡片 */
.seo-encyclopedia {
  margin-top: 36px;
  background: var(--bg-muted);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 24px;
}

.seo-encyclopedia h3 {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 12px;
}

.formula-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
  font-size: 13px;
  color: var(--text-body);
}

.formula-grid code {
  font-family: var(--font-mono);
  background: var(--brand-light);
  border: 1px solid var(--border-brand);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--brand-primary);
  font-weight: 600;
}

/* ==========================================================================
   4. 四大核心功能特色 (Features Grid)
   ========================================================================== */
.features-section {
  padding: 80px 0;
  background: var(--bg-muted);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  display: flex;
  flex-direction: column;
  gap: 14px;
  position: relative;
  box-shadow: var(--shadow-sm);
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-brand);
  box-shadow: var(--shadow-card-hover);
}

.feature-icon-box {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  background: var(--brand-light);
  border: 1px solid var(--border-brand);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  color: var(--brand-primary);
}

.feature-card h3 {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-main);
}

.feature-card p {
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.65;
}

/* ==========================================================================
   5. 痛点对比区 (Comparison Section)
   ========================================================================== */
.comparison-section {
  padding: 80px 0;
  background: var(--bg-page);
}

.comparison-table-wrapper {
  max-width: 980px;
  margin: 0 auto;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--border-light);
  background: var(--bg-card);
  box-shadow: var(--shadow-card);
}

.comp-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

.comp-table th,
.comp-table td {
  padding: 18px 24px;
  border-bottom: 1px solid var(--border-light);
  font-size: 14px;
}

.comp-table th {
  background: #F1F5F9;
  color: var(--text-muted);
  font-weight: 700;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.comp-table th.col-highlight {
  background: var(--brand-light);
  color: var(--brand-primary);
  font-weight: 700;
  border-left: 2px solid var(--brand-primary);
}

.comp-table td.col-highlight {
  background: rgba(0, 143, 215, 0.03);
  font-weight: 600;
  color: var(--text-main);
  border-left: 2px solid rgba(0, 143, 215, 0.2);
}

.comp-table tr:last-child td {
  border-bottom: none;
}

.badge-tag {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 700;
}

.badge-tag.bad {
  background: var(--accent-rose-bg);
  color: var(--accent-rose);
}

.badge-tag.good {
  background: var(--accent-emerald-bg);
  color: var(--accent-emerald);
}

/* ==========================================================================
   6. 常见问答 FAQ (面向人类与 AI 大模型)
   ========================================================================== */
.faq-section {
  padding: 80px 0;
  background: var(--bg-muted);
}

.faq-list {
  max-width: 820px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 22px 28px;
  box-shadow: var(--shadow-xs);
  transition: all 0.2s ease;
}

.faq-item:hover {
  border-color: var(--border-brand);
  box-shadow: var(--shadow-sm);
}

.faq-item h3 {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.faq-item h3::before {
  content: "Q";
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  background: var(--brand-light);
  color: var(--brand-primary);
  border: 1px solid var(--border-brand);
  border-radius: 6px;
  font-size: 13px;
  font-weight: 800;
  font-family: var(--font-mono);
}

.faq-item p {
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.65;
  padding-left: 34px;
}

/* ==========================================================================
   7. 底部 CTA 转化横幅
   ========================================================================== */
.bottom-cta {
  padding: 80px 0;
  background: radial-gradient(circle at center, rgba(0, 143, 215, 0.08) 0%, transparent 70%);
  text-align: center;
}

.bottom-cta-box {
  max-width: 800px;
  margin: 0 auto;
  background: linear-gradient(135deg, #EBF6FD 0%, #F4FAFF 100%);
  border: 1px solid var(--border-brand);
  box-shadow: var(--shadow-card);
  border-radius: var(--radius-lg);
  padding: 48px 36px;
}

.bottom-cta-box h2 {
  font-size: 32px;
  font-weight: 900;
  margin-bottom: 14px;
  color: var(--text-main);
}

.bottom-cta-box p {
  font-size: 16px;
  color: var(--text-muted);
  max-width: 560px;
  margin: 0 auto 32px;
}

/* ==========================================================================
   8. 页脚 (Footer)
   ========================================================================== */
footer {
  border-top: 1px solid var(--border-light);
  background: var(--bg-muted);
  padding: 40px 0 30px;
  font-size: 13px;
  color: var(--text-muted);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 20px;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.footer-logo {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.footer-logo .logo-img-sm {
  height: 24px;
  width: auto;
  object-fit: contain;
}

.footer-links {
  display: flex;
  gap: 20px;
}

.footer-links a {
  color: var(--text-muted);
  transition: color 0.2s;
}

.footer-links a:hover {
  color: var(--brand-primary);
}

/* 响应式适配 (Mobile & Tablet) */
@media (max-width: 768px) {
  .hero-title {
    font-size: 32px;
  }
  .hero-stats {
    grid-template-columns: repeat(2, 1fr);
  }
  .nav-links {
    display: none; /* 移动端精简模式 */
  }
  .calc-container {
    padding: 20px;
  }
  .calc-result-board {
    grid-template-columns: 1fr;
  }
  .comp-table {
    display: block;
    overflow-x: auto;
  }
  .footer-content {
    flex-direction: column;
    text-align: center;
  }
}