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

:root {
  --deep-blue: #1A365D;
  --tech-blue: #3182CE;
  --white: #FFFFFF;
  --light-gray: #F7FAFC;
  --bright-blue: #63B3ED;
  --dark-gray: #2D3748;
  --medium-gray: #718096;
  --card-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --card-shadow-hover: 0 10px 25px rgba(0, 0, 0, 0.15);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Inter', 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  color: var(--dark-gray);
  background-color: var(--white);
  overflow-x: hidden;
}

.navbar {
  position: fixed;
  top: 0;
  width: 100%;
  background: rgba(26, 54, 93, 0.95);
  backdrop-filter: blur(10px);
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--white);
  text-decoration: none;
  letter-spacing: -0.5px;
}

.nav-menu {
  display: flex;
  gap: 2.5rem;
  list-style: none;
}

.nav-link {
  color: var(--light-gray);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  transition: color 0.3s ease;
  position: relative;
}

.nav-link:hover,
.nav-link.active {
  color: var(--bright-blue);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--bright-blue);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  flex-direction: column;
  gap: 5px;
}

.nav-toggle span {
  width: 25px;
  height: 3px;
  background: var(--white);
  border-radius: 3px;
  transition: all 0.3s ease;
}

.hero {
  min-height: 100vh;
  background: linear-gradient(135deg, rgba(26, 54, 93, 0.9), rgba(49, 130, 206, 0.85)), url('https://hpi-hub.tos-cn-beijing.volces.com/static/gif/17-23-54-364_512.gif');
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 2rem;
  margin-top: 60px;
}

.hero-content {
  max-width: 900px;
  color: var(--white);
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 1.5rem;
  line-height: 1.2;
  letter-spacing: -1px;
}

.hero-subtitle {
  font-size: 1.3rem;
  margin-bottom: 3rem;
  color: var(--light-gray);
  font-weight: 400;
  line-height: 1.8;
}

.btn-primary {
  display: inline-block;
  padding: 1rem 2.5rem;
  background: var(--bright-blue);
  color: var(--white);
  text-decoration: none;
  border-radius: 50px;
  font-weight: 600;
  font-size: 1.1rem;
  transition: all 0.3s ease;
  box-shadow: 0 4px 15px rgba(99, 179, 237, 0.3);
}

.btn-primary:hover {
  background: var(--tech-blue);
  transform: translateY(-3px);
  box-shadow: 0 8px 25px rgba(99, 179, 237, 0.4);
}

.section {
  padding: 6rem 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.section-title {
  font-size: 2.5rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 1rem;
  color: var(--deep-blue);
}

.section-subtitle {
  text-align: center;
  font-size: 1.1rem;
  color: var(--medium-gray);
  margin-bottom: 4rem;
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
}

.cards-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2.5rem;
  margin-top: 3rem;
}

.card {
  background: var(--white);
  border-radius: 16px;
  padding: 2.5rem;
  box-shadow: var(--card-shadow);
  transition: all 0.3s ease;
  border: 1px solid rgba(49, 130, 206, 0.1);
}

.card:hover {
  transform: translateY(-8px);
  box-shadow: var(--card-shadow-hover);
  border-color: var(--bright-blue);
}

.card-icon {
  width: 80px;
  height: 80px;
  margin-bottom: 1.5rem;
  border-radius: 12px;
  object-fit: cover;
}

.card-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--deep-blue);
}

.card-description {
  font-size: 1rem;
  line-height: 1.7;
  color: var(--medium-gray);
}

.trust-section {
  background: var(--light-gray);
  padding: 4rem 2rem;
  text-align: center;
}

.trust-content {
  max-width: 900px;
  margin: 0 auto;
}

.trust-text {
  font-size: 1.2rem;
  color: var(--medium-gray);
  line-height: 1.8;
}

.service-card {
  background: var(--white);
  border-radius: 16px;
  padding: 2rem;
  box-shadow: var(--card-shadow);
  transition: all 0.3s ease;
  border-left: 4px solid var(--tech-blue);
}

.service-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--card-shadow-hover);
  border-left-color: var(--bright-blue);
}

.service-title {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 0.8rem;
  color: var(--deep-blue);
}

.service-description {
  font-size: 0.95rem;
  color: var(--medium-gray);
  line-height: 1.6;
}

.about-content {
  max-width: 900px;
  margin: 0 auto;
  text-align: center;
}

.about-text {
  font-size: 1.1rem;
  line-height: 1.9;
  color: var(--medium-gray);
  margin-bottom: 3rem;
}

.principles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin: 3rem 0;
}

.principle-item {
  text-align: center;
  padding: 1.5rem;
}

.principle-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  color: var(--tech-blue);
}

.principle-title {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--deep-blue);
}

.principle-text {
  font-size: 0.95rem;
  color: var(--medium-gray);
}

.team-image {
  width: 100%;
  max-width: 800px;
  height: 400px;
  object-fit: cover;
  border-radius: 16px;
  margin: 3rem auto;
  display: block;
  box-shadow: var(--card-shadow);
}

.case-card {
  background: var(--white);
  border-radius: 16px;
  overflow: hidden;
  box-shadow: var(--card-shadow);
  transition: all 0.3s ease;
}

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

.case-image {
  width: 100%;
  height: 220px;
  object-fit: cover;
}

.case-content {
  padding: 2rem;
}

.case-title {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--deep-blue);
}

.case-scenario {
  font-size: 0.95rem;
  color: var(--medium-gray);
  margin-bottom: 1rem;
  line-height: 1.6;
}

.case-result {
  font-size: 0.95rem;
  color: var(--tech-blue);
  font-weight: 600;
  line-height: 1.6;
}

.insight-card {
  background: var(--white);
  border-radius: 16px;
  padding: 2.5rem;
  box-shadow: var(--card-shadow);
  transition: all 0.3s ease;
  border-top: 4px solid var(--bright-blue);
}

.insight-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--card-shadow-hover);
}

.insight-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--deep-blue);
}

.insight-summary {
  font-size: 1rem;
  color: var(--medium-gray);
  line-height: 1.7;
}

.footer {
  background: var(--deep-blue);
  color: var(--white);
  text-align: center;
  padding: 2rem;
  margin-top: 4rem;
}

.footer-text {
  font-size: 0.95rem;
  font-weight: 500;
}

@media (max-width: 768px) {
  .nav-menu {
    position: fixed;
    left: -100%;
    top: 60px;
    flex-direction: column;
    background: rgba(26, 54, 93, 0.98);
    width: 100%;
    text-align: center;
    transition: left 0.3s ease;
    padding: 2rem 0;
    gap: 1.5rem;
  }

  .nav-menu.active {
    left: 0;
  }

  .nav-toggle {
    display: flex;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-subtitle {
    font-size: 1.1rem;
  }

  .section {
    padding: 4rem 1.5rem;
  }

  .section-title {
    font-size: 2rem;
  }

  .cards-container {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .card {
    padding: 2rem;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 2rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

  .btn-primary {
    padding: 0.8rem 2rem;
    font-size: 1rem;
  }

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