:root {
  --color-primary: #88A9C3;
  --color-secondary: #D7C9B1;
  --color-accent: #006D77;
  --color-light: #F5F5F5;
  --color-warm: #F8D7DA;
  --color-text-dark: #333333;
  --color-text-medium: #666666;
  --color-text-light: #999999;
  --font-sans: 'Inter', Tahoma, Arial, Roboto, "Droid Sans", "Helvetica Neue", sans-serif;
  --transition-smooth: all 0.3s ease;
  --shadow-soft: 0 4px 20px rgba(0,0,0,0.05);
  --shadow-medium: 0 8px 30px rgba(0,0,0,0.1);
}

body {
  font-family: var(--font-sans);
  color: var(--color-text-dark);
  line-height: 1.6;
  background-color: white;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 500;
  line-height: 1.2;
  margin-bottom: 1rem;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: var(--transition-smooth);
}

a:hover {
  color: #004e56;
}

.btn-primary {
  background-color: var(--color-accent);
  color: white;
  padding: 0.875rem 1.75rem;
  border-radius: 4px;
  font-weight: 500;
  font-size: 1rem;
  letter-spacing: 0.025em;
  transition: var(--transition-smooth);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 160px;
  box-shadow: 0 2px 10px rgba(0,109,119,0.2);
}

.btn-primary:hover {
  background-color: #005a63;
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(0,109,119,0.3);
}

.btn-secondary {
  background-color: white;
  color: var(--color-text-dark);
  border: 1px solid #E2E8F0;
  padding: 0.875rem 1.75rem;
  border-radius: 4px;
  font-weight: 500;
  font-size: 1rem;
  letter-spacing: 0.025em;
  transition: var(--transition-smooth);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 160px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.btn-secondary:hover {
  background-color: #F5F7FA;
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(0,0,0,0.08);
}

/* Nordic style Hero title */
.hero-title {
  font-size: 3.5rem;
  line-height: 1.1;
  font-weight: 600;
  color: var(--color-text-dark);
  margin-bottom: 1.5rem;
  letter-spacing: -0.02em;
}

/* Subtitle styles */
.hero-subtitle {
  font-size: 1.25rem;
  line-height: 1.6;
  color: var(--color-text-medium);
  margin-bottom: 2rem;
  max-width: 600px;
  font-weight: 400;
}

/* Hero 图片样式 */
.hero-image {
  width: 100%;
  max-width: 450px;
  height: auto;
  border-radius: 8px;
  box-shadow: var(--shadow-medium);
  transition: transform 0.5s ease;
}

.image-container {
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
}

.image-container::before {
  content: '';
  position: absolute;
  top: 20px;
  left: 20px;
  width: 100%;
  height: 100%;
  border-radius: 8px;
  background-color: var(--color-secondary);
  opacity: 0.2;
  z-index: -1;
}

.content-section {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  padding: 6rem 2rem;
}

.button-group {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin-top: 2rem;
}

.section-light {
  padding-top: 1rem; 
  background-color: white;
  padding: 6rem 0;
  width: 100%;
  box-sizing: border-box;
  position: relative;
}

.section-light::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: linear-gradient(135deg, rgba(136,169,195,0.05) 0%, rgba(255,255,255,0) 100%);
  z-index: -1;
}

.section-dark {
  background-color: var(--color-light);
  padding: 6rem 0;
  width: 100%;
  box-sizing: border-box;
  position: relative;
}

.section-dark::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: linear-gradient(135deg, rgba(215,201,177,0.1) 0%, rgba(245,245,245,0) 100%);
  z-index: -1;
}

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

.card {
  background-color: white;
  border-radius: 8px;
  box-shadow: var(--shadow-soft);
  transition: var(--transition-smooth);
  overflow: hidden;
}

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

@media (max-width: 768px) {
  .content-section {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 2rem;
    padding: 4rem 1.5rem;
  }
  
  .hero-image {
    margin-top: 2rem;
    max-width: 100%;
  }
  
  .hero-title {
    font-size: 2.5rem;
  }
  
  .button-group {
    justify-content: center;
  }
}

@media (max-width: 480px) {
  .button-group {
    flex-direction: column;
    gap: 0.75rem;
  }
  
  .btn-primary,
  .btn-secondary {
    width: 100%;
    min-width: unset;
  }
  
  .section-light,
  .section-dark {
    padding: 4rem 0;
  }
}

@media (min-width: 640px) {
  .section-light {
    padding-top: 2rem; 
  }
}

/* Micro-interaction animations */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.animate-fade-in {
  animation: fadeIn 0.8s ease forwards;
}

.delay-100 { animation-delay: 0.1s; }
.delay-200 { animation-delay: 0.2s; }
.delay-300 { animation-delay: 0.3s; }
.delay-400 { animation-delay: 0.4s; }
.delay-500 { animation-delay: 0.5s; }

/* Nordic style decorative elements */
.nordic-shape {
  position: absolute;
  z-index: -1;
  opacity: 0.1;
}

.nordic-shape.circle {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  background-color: var(--color-primary);
}

.nordic-shape.triangle {
  width: 0;
  height: 0;
  border-left: 100px solid transparent;
  border-right: 100px solid transparent;
  border-bottom: 173px solid var(--color-secondary);
}

.nordic-shape.line {
  width: 150px;
  height: 2px;
  background-color: var(--color-accent);
}

.book-card {
  transition: var(--transition-smooth);
  background: white;
  border-radius: 8px;
  overflow: hidden;
}

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

.book-cover {
  transition: var(--transition-smooth);
  max-width: 100%;
  height: auto;
}

.book-detail-cover {
  width: 100%;
  max-width: 300px;
  height: auto;
  margin: 0 auto 2rem;
  border-radius: 8px;
  box-shadow: var(--shadow-soft);
  transition: var(--transition-smooth);
}

@media (max-width: 768px) {
  .book-detail-cover {
    max-width: 220px;
  }
}

.book-card:hover .book-cover {
  transform: scale(1.05);
}

h1 {
  font-size: 2rem;
  line-height: 1.2;
  font-weight: 600;
  color: var(--color-text-dark);
  margin-bottom: 1.5rem;
}

h2 {
  font-size: 1.5rem;
  line-height: 1.2;
  font-weight: 600;
  color: var(--color-text-dark);
  margin-bottom: 1.5rem;
}

.download-link {
  color: blue;
  text-decoration: underline;
  transition: var(--transition-smooth);
}

.download-link:hover {
  color: #004e56;
}