/* ==========================================================================
   MK (Sports Technology Co., Ltd.) - Main Stylesheet
   Version: 1.0.1
   Author: Senior Front-End Engineer & SEO/CRO Expert
   Design System: Modern Sports Tech / Clean B2B Trust
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. CSS Custom Properties (Design System Tokens)
   -------------------------------------------------------------------------- */
:root {
  /* Brand Color Palette */
  --primary-900: #0f172a; /* Deep Navy Background/Text */
  --primary-800: #1e293b; /* Dark Slate Blue */
  --primary-700: #334155; /* Slate Border/Muted Elements */
  --primary-600: #0284c7; /* Vibrant Tech Blue */
  --primary-500: #0ea5e9; /* Light Tech Blue */
  
  --accent-500: #f97316;  /* High-Conversion Energy Orange */
  --accent-600: #ea580c;  /* Hover Orange */
  --accent-soft: rgba(249, 115, 22, 0.1);

  --neutral-100: #ffffff; /* Pure White */
  --neutral-200: #f8fafc; /* Warm Light Gray Background */
  --neutral-300: #f1f5f9; /* Subtle Card Fill */
  --neutral-400: #e2e8f0; /* Light Divider/Border */
  --neutral-600: #64748b; /* Secondary Body Text */
  --neutral-900: #020617; /* High-contrast Heading Text */

  /* Typography */
  --font-main: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Inter", -apple-system, BlinkMacSystemFont, sans-serif;
  
  /* Layout Spacing */
  --container-max: 1280px;
  --section-padding-y: 96px;
  --section-padding-y-mobile: 60px;
  --header-height: 80px;

  /* Shadows & Depth */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 25px -5px rgba(2, 132, 199, 0.12), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
  --shadow-hover: 0 20px 30px -10px rgba(15, 23, 42, 0.18);
  --shadow-glow: 0 0 25px rgba(249, 115, 22, 0.35);

  /* Micro-interactions */
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;
}

/* --------------------------------------------------------------------------
   2. Modern CSS Reset & Baseline
   -------------------------------------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-main);
  background-color: var(--neutral-100);
  color: var(--primary-800);
  line-height: 1.65;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: inherit;
  text-decoration: none !important; /* 彻底移除下划线 */
  transition: color var(--transition-fast);
}

button, input, select, textarea {
  font: inherit;
  border: none;
  outline: none;
}

/* --------------------------------------------------------------------------
   3. Common Layout & Utility Classes
   -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.section {
  padding-top: var(--section-padding-y);
  padding-bottom: var(--section-padding-y);
}

.section-bg-alt {
  background-color: var(--neutral-200);
}

.section-bg-dark {
  background-color: var(--primary-900);
  color: var(--neutral-100);
}

/* Section Header Typography */
.section-header {
  text-align: center;
  max-width: 760px;
  margin: 0 auto 64px auto;
}

.section-subtitle {
  display: inline-block;
  font-size: 0.875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--primary-600);
  background-color: rgba(2, 132, 199, 0.08);
  padding: 6px 16px;
  border-radius: var(--radius-full);
  margin-bottom: 16px;
}

.section-bg-dark .section-subtitle {
  color: var(--primary-500);
  background-color: rgba(14, 165, 233, 0.15);
}

.section-title {
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--neutral-900);
  line-height: 1.25;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.section-bg-dark .section-title {
  color: var(--neutral-100);
}

.section-desc {
  font-size: 1.125rem;
  color: var(--neutral-600);
}

.section-bg-dark .section-desc {
  color: var(--neutral-400);
}

/* --------------------------------------------------------------------------
   4. High-Conversion Buttons & Interactive Elements
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
  padding: 14px 28px;
  border-radius: var(--radius-md);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition-normal);
  text-align: center;
  gap: 8px;
}

.btn-primary {
  background-color: var(--accent-500);
  color: var(--neutral-100);
  box-shadow: 0 4px 14px rgba(249, 115, 22, 0.35);
}

.btn-primary:hover {
  background-color: var(--accent-600);
  transform: scale(1.03);
  box-shadow: var(--shadow-glow);
}

.btn-secondary {
  background-color: rgba(255, 255, 255, 0.1);
  color: var(--neutral-100);
  border: 1px solid rgba(255, 255, 255, 0.25);
  backdrop-filter: blur(8px);
}

.btn-secondary:hover {
  background-color: var(--neutral-100);
  color: var(--primary-900);
  transform: scale(1.03);
}

.btn-outline {
  background-color: transparent;
  color: var(--primary-600);
  border: 2px solid var(--primary-600);
}

.btn-outline:hover {
  background-color: var(--primary-600);
  color: var(--neutral-100);
  transform: scale(1.03);
}

/* --------------------------------------------------------------------------
   5. Sticky Header & Navigation Bar
   -------------------------------------------------------------------------- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  background-color: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--neutral-400);
  z-index: 1000;
  transition: all var(--transition-normal);
}

.header-scrolled {
  box-shadow: var(--shadow-md);
  height: 70px;
}

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

/* SVG Text Logo */
.brand-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.5rem;
  font-weight: 900;
  color: var(--primary-900);
  letter-spacing: -0.03em;
}

.brand-logo svg {
  width: 36px;
  height: 36px;
  fill: var(--primary-600);
}

.brand-logo span.highlight {
  color: var(--accent-500);
}

/* Navigation Links */
.nav-menu {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-link {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--primary-800);
  position: relative;
  padding: 8px 0;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--accent-500);
  transition: width var(--transition-fast);
}

.nav-link:hover {
  color: var(--accent-500);
}

.nav-link:hover::after {
  width: 100%;
}

.header-cta {
  display: flex;
  align-items: center;
  gap: 16px;
}

/* Mobile Hamburger Toggle */
.mobile-toggle {
  display: none;
  background: none;
  cursor: pointer;
  padding: 8px;
  flex-direction: column;
  gap: 6px;
}

.mobile-toggle span {
  display: block;
  width: 26px;
  height: 2.5px;
  background-color: var(--primary-900);
  border-radius: 2px;
  transition: all var(--transition-fast);
}

/* --------------------------------------------------------------------------
   6. Hero Section
   -------------------------------------------------------------------------- */
.hero {
  position: relative;
  min-height: 100vh;
  padding-top: calc(var(--header-height) + 60px);
  padding-bottom: 80px;
  display: flex;
  align-items: center;
  background-color: var(--primary-900);
  color: var(--neutral-100);
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.28;
  z-index: 1;
}

.hero-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: radial-gradient(circle at 70% 30%, rgba(2, 132, 199, 0.2) 0%, rgba(15, 23, 42, 0.9) 70%);
  z-index: 2;
}

.hero-container {
  position: relative;
  z-index: 3;
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
}

.hero-content h1 {
  font-size: 3.25rem;
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 24px;
}

.hero-content h1 span.accent {
  color: var(--accent-500);
  background: linear-gradient(135deg, #f97316 0%, #fb923c 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--neutral-400);
  margin-bottom: 40px;
  line-height: 1.6;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid rgba(255, 255, 255, 0.15);
}

.stat-item .stat-number {
  font-size: 2rem;
  font-weight: 800;
  color: var(--primary-500);
  line-height: 1;
  margin-bottom: 6px;
}

.stat-item .stat-label {
  font-size: 0.875rem;
  color: var(--neutral-400);
}

.hero-card-preview {
  background: rgba(30, 41, 59, 0.7);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: var(--radius-lg);
  padding: 16px;
  backdrop-filter: blur(16px);
  box-shadow: var(--shadow-hover);
}

.hero-card-preview img {
  border-radius: var(--radius-md);
  width: 100%;
}

/* --------------------------------------------------------------------------
   7. Pain Points Section
   -------------------------------------------------------------------------- */
.pain-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 32px;
}

.pain-card {
  background-color: var(--neutral-100);
  border: 1px solid var(--neutral-400);
  border-radius: var(--radius-md);
  padding: 36px 28px;
  transition: all var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.pain-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background-color: var(--accent-500);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.pain-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

.pain-card:hover::before {
  opacity: 1;
}

.pain-icon {
  width: 52px;
  height: 52px;
  background-color: var(--accent-soft);
  color: var(--accent-500);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 20px;
}

.pain-card h3 {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--neutral-900);
  margin-bottom: 12px;
}

.pain-card p {
  color: var(--neutral-600);
  font-size: 0.975rem;
}

/* --------------------------------------------------------------------------
   8. Solutions & Products Section
   -------------------------------------------------------------------------- */
.solutions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
  gap: 32px;
}

.solution-card {
  background-color: var(--neutral-100);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--neutral-400);
  transition: all var(--transition-normal);
  display: flex;
  flex-direction: column;
}

.solution-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-hover);
}

.solution-img-wrapper {
  position: relative;
  height: 220px;
  overflow: hidden;
}

.solution-img-wrapper img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.solution-card:hover .solution-img-wrapper img {
  transform: scale(1.08);
}

.solution-tag {
  position: absolute;
  top: 16px;
  left: 16px;
  background-color: var(--primary-900);
  color: var(--neutral-100);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: var(--radius-full);
}

.solution-content {
  padding: 32px;
  flex-grow: 1;
  display: flex;
  flex-direction: column;
}

.solution-content h3 {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--neutral-900);
  margin-bottom: 12px;
}

.solution-content p {
  color: var(--neutral-600);
  font-size: 0.95rem;
  margin-bottom: 24px;
}

.solution-features {
  list-style: none;
  margin-bottom: 28px;
  margin-top: auto;
}

.solution-features li {
  font-size: 0.9rem;
  color: var(--primary-800);
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.solution-features li::before {
  content: '✓';
  color: var(--primary-600);
  font-weight: 900;
}

/* --------------------------------------------------------------------------
   9. Social Proof & E-E-A-T Section
   -------------------------------------------------------------------------- */
.proof-stats-bar {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 24px;
  background-color: var(--neutral-100);
  padding: 40px;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  margin-bottom: 64px;
  text-align: center;
}

.proof-stat-val {
  font-size: 2.75rem;
  font-weight: 900;
  color: var(--primary-600);
  line-height: 1;
  margin-bottom: 8px;
}

.proof-stat-desc {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--neutral-600);
}

.cases-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 32px;
}

.case-card {
  background-color: var(--neutral-100);
  border-radius: var(--radius-md);
  padding: 28px;
  border: 1px solid var(--neutral-400);
}

.case-quote {
  font-size: 0.975rem;
  color: var(--primary-800);
  font-style: italic;
  margin-bottom: 20px;
  line-height: 1.7;
}

.case-author {
  display: flex;
  align-items: center;
  gap: 14px;
}

.case-author-avatar {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  object-fit: cover;
}

.case-author-info h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--neutral-900);
}

.case-author-info p {
  font-size: 0.85rem;
  color: var(--neutral-600);
}

/* --------------------------------------------------------------------------
   10. About Us & Local SEO Section
   -------------------------------------------------------------------------- */
.about-wrapper {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
}

.about-text h2 {
  font-size: 2.25rem;
  font-weight: 800;
  margin-bottom: 20px;
  color: var(--neutral-900);
}

.about-text p {
  color: var(--neutral-600);
  margin-bottom: 24px;
  font-size: 1.05rem;
}

.about-info-list {
  list-style: none;
  margin-top: 32px;
}

.about-info-item {
  display: flex;
  gap: 16px;
  margin-bottom: 20px;
}

.about-info-icon {
  width: 40px;
  height: 40px;
  background-color: rgba(2, 132, 199, 0.1);
  color: var(--primary-600);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  flex-shrink: 0;
}

.about-info-details h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--neutral-900);
}

.about-info-details p {
  font-size: 0.95rem;
  color: var(--neutral-600);
  margin-bottom: 0;
}

.about-media-frame {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.about-media-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* --------------------------------------------------------------------------
   11. FAQ Accordion Section
   -------------------------------------------------------------------------- */
.faq-container {
  max-width: 840px;
  margin: 0 auto;
}

.faq-item {
  background-color: var(--neutral-100);
  border: 1px solid var(--neutral-400);
  border-radius: var(--radius-md);
  margin-bottom: 16px;
  overflow: hidden;
  transition: all var(--transition-fast);
}

.faq-item:hover {
  border-color: var(--primary-600);
}

.faq-question {
  width: 100%;
  padding: 24px;
  text-align: left;
  background: none;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--neutral-900);
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  gap: 16px;
}

.faq-toggle-icon {
  font-size: 1.5rem;
  color: var(--primary-600);
  transition: transform var(--transition-fast);
}

.faq-item.active .faq-toggle-icon {
  transform: rotate(45deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-normal), padding var(--transition-normal);
  background-color: var(--neutral-200);
}

.faq-item.active .faq-answer {
  max-height: 300px;
  padding: 0 24px 24px 24px;
}

.faq-answer p {
  font-size: 0.975rem;
  color: var(--neutral-600);
  line-height: 1.7;
}

/* --------------------------------------------------------------------------
   12. Final CTA & Lead Generation Form
   -------------------------------------------------------------------------- */
.cta-box {
  background: linear-gradient(135deg, var(--primary-900) 0%, var(--primary-800) 100%);
  border-radius: var(--radius-lg);
  padding: 64px 48px;
  color: var(--neutral-100);
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
  box-shadow: var(--shadow-hover);
  position: relative;
  overflow: hidden;
}

.cta-box::after {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(249, 115, 22, 0.15) 0%, rgba(0,0,0,0) 70%);
  pointer-events: none;
}

.cta-content h2 {
  font-size: 2.25rem;
  font-weight: 800;
  margin-bottom: 16px;
  line-height: 1.2;
}

.cta-content p {
  color: var(--neutral-400);
  font-size: 1.05rem;
  margin-bottom: 32px;
}

.cta-form {
  background-color: var(--neutral-100);
  padding: 32px;
  border-radius: var(--radius-md);
  color: var(--primary-900);
  box-shadow: var(--shadow-lg);
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 0.875rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--neutral-900);
}

.form-control {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--neutral-400);
  border-radius: var(--radius-sm);
  background-color: var(--neutral-200);
  transition: border-color var(--transition-fast);
}

.form-control:focus {
  border-color: var(--primary-600);
  background-color: var(--neutral-100);
}

.form-submit-btn {
  width: 100%;
  padding: 16px;
  font-size: 1.05rem;
}

/* --------------------------------------------------------------------------
   13. Footer Section
   -------------------------------------------------------------------------- */
.footer {
  background-color: var(--neutral-900);
  color: var(--neutral-400);
  padding-top: 64px;
  padding-bottom: 32px;
  border-top: 1px solid var(--primary-700);
  font-size: 0.9rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 48px;
  margin-bottom: 48px;
}

.footer-brand p {
  margin-top: 16px;
  color: var(--neutral-400);
  font-size: 0.9rem;
  line-height: 1.6;
}

.footer-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--neutral-100);
  margin-bottom: 20px;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 12px;
}

.footer-links a {
  text-decoration: none !important;
}

.footer-links a:hover {
  color: var(--accent-500);
}

.footer-bottom {
  padding-top: 32px;
  border-top: 1px solid var(--primary-700);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-bottom a {
  text-decoration: none !important; /* 强制去除了页尾 ICP 备案、隐私政策、服务条款等的下划线 */
  color: var(--neutral-400);
  transition: color var(--transition-fast);
}

.footer-bottom a:hover {
  color: var(--accent-500);
  text-decoration: none !important;
}

/* --------------------------------------------------------------------------
   14. Mobile-First Responsive Breakpoints
   -------------------------------------------------------------------------- */
@media (max-width: 1024px) {
  .hero-container {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .hero-actions {
    justify-content: center;
  }

  .hero-stats {
    justify-content: center;
  }

  .hero-card-preview {
    max-width: 540px;
    margin: 0 auto;
  }

  .about-wrapper {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .cta-box {
    grid-template-columns: 1fr;
    padding: 40px 24px;
  }

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

@media (max-width: 768px) {
  :root {
    --section-padding-y: var(--section-padding-y-mobile);
  }

  .section-title {
    font-size: 1.75rem;
  }

  .mobile-toggle {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    top: var(--header-height);
    left: 0;
    width: 100%;
    background-color: var(--neutral-100);
    flex-direction: column;
    padding: 32px 24px;
    gap: 20px;
    box-shadow: var(--shadow-lg);
    transform: translateY(-150%);
    transition: transform var(--transition-normal);
  }

  .nav-menu.is-active {
    transform: translateY(0);
  }

  .header-cta .btn {
    display: none;
  }

  .hero-content h1 {
    font-size: 2.25rem;
  }

  .solutions-grid,
  .pain-grid,
  .cases-grid {
    grid-template-columns: 1fr;
  }

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

  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }
}