:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1e40af;
  --color-text: #1f2937;
  --color-text-light: #6b7280;
  --color-bg: #ffffff;
  --color-bg-alt: #f9fafb;
  --color-border: #e5e7eb;
  --color-accent: #10b981;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-serif: Georgia, Cambria, "Times New Roman", Times, serif;

  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 4rem;

  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 1rem;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);

  --container-max: 1200px;
  --container-padding: var(--spacing-sm);
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-text: #f9fafb;
    --color-text-light: #9ca3af;
    --color-bg: #111827;
    --color-bg-alt: #1f2937;
    --color-border: #374151;
  }
}

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-text);
  background: linear-gradient(to bottom, #f9fafb 0%, #ffffff 50%, #f9fafb 100%);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

@media (min-width: 768px) {
  :root {
    --container-padding: var(--spacing-lg);
  }
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
}

h1 {
  font-size: 2.25rem;
  margin-bottom: var(--spacing-lg);
}

h2 {
  font-size: 1.875rem;
}

h3 {
  font-size: 1.5rem;
}

h4 {
  font-size: 1.25rem;
}

@media (min-width: 768px) {
  h1 {
    font-size: 3rem;
  }

  h2 {
    font-size: 2.25rem;
  }

  h3 {
    font-size: 1.875rem;
  }
}

p {
  margin-bottom: var(--spacing-md);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--color-primary-dark);
  text-decoration: underline;
}

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

.main-nav {
  background-color: rgba(255, 255, 255, 0.95);
  border-bottom: 1px solid #e5e7eb;
  padding: var(--spacing-sm) 0;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(10px);
  box-shadow: 0 2px 8px 0 rgba(0, 0, 0, 0.08);
}

.main-nav .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.main-nav .logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
}

.main-nav .logo:hover {
  color: var(--color-primary);
  text-decoration: none;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: var(--spacing-md);
  align-items: center;
}

.nav-links a {
  color: var(--color-text-light);
  font-weight: 500;
  padding: var(--spacing-xs) 0;
  text-decoration: none;
}

.nav-links a:hover {
  color: var(--color-primary);
  text-decoration: none;
}

@media (max-width: 767px) {
  .nav-links {
    gap: var(--spacing-sm);
    font-size: 0.875rem;
  }
}

.hero {
  background: linear-gradient(135deg, #2563eb 0%, #1e40af 100%);
  color: white;
  padding: 5rem 0;
  text-align: center;
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.15);
  margin-bottom: 0;
}

.hero h1 {
  color: white;
}

.hero h1 {
  margin-bottom: var(--spacing-md);
}

.hero p {
  font-size: 1.25rem;
  color: rgba(255, 255, 255, 0.95);
  max-width: 700px;
  margin: 0 auto var(--spacing-lg);
}

.hero .cta-buttons {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  background-color: var(--color-primary);
  color: white;
  border-radius: var(--radius-md);
  font-weight: 600;
  text-decoration: none;
  transition: all 0.2s ease;
  border: 2px solid var(--color-primary);
}

.btn:hover {
  background-color: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background-color: transparent;
  color: white !important;
  border: 2px solid white;
}

.btn-secondary:hover {
  background-color: white;
  color: var(--color-primary);
  border-color: white;
}

.section {
  padding: var(--spacing-xl) 0;
}

.section-title {
  text-align: center;
  margin-bottom: var(--spacing-xl);
}

.grid {
  display: grid;
  gap: var(--spacing-lg);
  grid-template-columns: 1fr;
}

@media (min-width: 640px) {
  .grid-2 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 768px) {
  .grid-3 {
    grid-template-columns: repeat(3, 1fr);
  }

  .grid-4 {
    grid-template-columns: repeat(4, 1fr);
  }
}

.card {
  background-color: #ffffff;
  border: 1px solid #e5e7eb;
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  transition: all 0.3s ease;
  box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.08);
}

.card:hover {
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.12), 0 8px 10px -6px rgba(0, 0, 0, 0.08);
  transform: translateY(-6px);
  border-color: #d1d5db;
}

.card img {
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-md);
}

.card h3 {
  margin-bottom: var(--spacing-sm);
}

.card p {
  color: var(--color-text-light);
  font-size: 0.9375rem;
}

.book-card {
  display: flex;
  flex-direction: column;
}

.book-card img {
  aspect-ratio: 2/3;
  object-fit: cover;
  width: 100%;
}

.book-card .book-info {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.book-card .book-price {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-accent);
  margin-top: auto;
  padding-top: var(--spacing-sm);
}

.blog-post {
  padding: var(--spacing-xl) 0;
}

.post-header {
  margin-bottom: var(--spacing-xl);
  text-align: center;
}

.post-meta {
  font-size: 0.875rem;
  color: var(--color-text-light);
  margin-bottom: var(--spacing-md);
}

.post-meta .separator {
  margin: 0 var(--spacing-xs);
}

.post-featured-image {
  margin-bottom: var(--spacing-xl);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.post-featured-image img {
  width: 100%;
  height: auto;
}

.post-content {
  font-family: var(--font-serif);
  font-size: 1.125rem;
  line-height: 1.8;
  max-width: 700px;
  margin: 0 auto;
}

.post-content h2 {
  margin-top: var(--spacing-xl);
  margin-bottom: var(--spacing-md);
}

.post-content h3 {
  margin-top: var(--spacing-lg);
  margin-bottom: var(--spacing-sm);
}

.post-content p {
  margin-bottom: var(--spacing-md);
}

.post-content ul,
.post-content ol {
  margin-bottom: var(--spacing-md);
  padding-left: var(--spacing-lg);
}

.post-content li {
  margin-bottom: var(--spacing-xs);
}

.post-content img {
  margin: var(--spacing-lg) auto;
  border-radius: var(--radius-md);
}

.post-content blockquote {
  border-left: 4px solid var(--color-primary);
  padding-left: var(--spacing-md);
  margin: var(--spacing-lg) 0;
  font-style: italic;
  color: var(--color-text-light);
}

.post-content code {
  background-color: var(--color-bg-alt);
  padding: 0.125rem 0.25rem;
  border-radius: var(--radius-sm);
  font-size: 0.875em;
  font-family: 'Courier New', monospace;
}

.post-content pre {
  background-color: var(--color-bg-alt);
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin-bottom: var(--spacing-md);
}

.post-content pre code {
  background: none;
  padding: 0;
}

.post-footer {
  margin-top: var(--spacing-2xl);
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--color-border);
}

.author-bio {
  max-width: 700px;
  margin: 0 auto;
  padding: var(--spacing-lg);
  background-color: var(--color-bg-alt);
  border-radius: var(--radius-lg);
}

.author-bio h3 {
  font-size: 1.25rem;
  margin-bottom: var(--spacing-sm);
}

.author-bio p {
  margin-bottom: var(--spacing-sm);
  font-size: 0.9375rem;
  color: var(--color-text-light);
}

.cta-link {
  display: inline-block;
  font-weight: 600;
  color: var(--color-primary);
  text-decoration: none;
  transition: all 0.2s ease;
}

.cta-link:hover {
  color: var(--color-primary-dark);
  transform: translateX(4px);
}

.main-footer {
  background: linear-gradient(to bottom, #1f2937 0%, #111827 100%);
  border-top: 3px solid #2563eb;
  padding: 3rem 0;
  margin-top: var(--spacing-2xl);
  text-align: center;
  box-shadow: 0 -10px 25px -5px rgba(0, 0, 0, 0.15);
}

.main-footer p {
  margin-bottom: var(--spacing-sm);
  color: #d1d5db;
  font-size: 0.875rem;
}

.main-footer a {
  color: #d1d5db;
  margin: 0 var(--spacing-xs);
  transition: color 0.2s ease;
}

.main-footer a:hover {
  color: #60a5fa;
  text-decoration: none;
}

.contact-form {
  max-width: 600px;
  margin: 0 auto;
}

.form-group {
  margin-bottom: var(--spacing-md);
}

.form-group label {
  display: block;
  margin-bottom: var(--spacing-xs);
  font-weight: 600;
  color: var(--color-text);
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 1rem;
  transition: border-color 0.2s ease;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-group textarea {
  min-height: 150px;
  resize: vertical;
}

.tbp-cta {
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  color: white;
  padding: var(--spacing-xl) var(--spacing-lg);
  border-radius: var(--radius-lg);
  text-align: center;
  margin: var(--spacing-2xl) 0;
}

.tbp-cta h3 {
  color: white;
  margin-bottom: var(--spacing-md);
}

.tbp-cta p {
  color: rgba(255, 255, 255, 0.9);
  margin-bottom: var(--spacing-lg);
  font-size: 1.125rem;
}

.tbp-cta .btn {
  background-color: white;
  color: var(--color-primary);
  border-color: white;
}

.tbp-cta .btn:hover {
  background-color: rgba(255, 255, 255, 0.9);
  color: var(--color-primary-dark);
}

@media (max-width: 767px) {
  .hero {
    padding: var(--spacing-xl) 0;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero p {
    font-size: 1.125rem;
  }

  .post-content {
    font-size: 1rem;
  }
}

@media print {
  .main-nav,
  .main-footer,
  .author-bio,
  .tbp-cta,
  .cta-buttons {
    display: none;
  }

  body {
    font-size: 12pt;
    line-height: 1.5;
  }

  h1 {
    font-size: 24pt;
  }

  h2 {
    font-size: 18pt;
  }

  a {
    color: #000;
    text-decoration: none;
  }

  a[href]:after {
    content: " (" attr(href) ")";
    font-size: 90%;
  }
}