:root {
  --primary: #28eefc;
  --secondary: #23499d;
  --on-primary: #111111;
  --on-secondary: #ffffff;
  --bg: #ffffff;
  --surface: #f5f7fa;
  --light: #eef1f6;
  --dark: #1a1a1a;
  --muted: #5b6472;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';
  color: var(--dark);
  background-color: var(--bg);
  line-height: 1.6;
}

h1, h2, h3, h4, h5, h6 {
  color: var(--dark);
  font-weight: 700;
}

.navbar {
  background-color: var(--bg);
  border-bottom: 1px solid var(--light);
}

.logo-img {
  max-height: 40px;
  width: auto;
}

.hero-section {
  background-color: var(--surface);
  padding-top: 70px;
  padding-bottom: 70px;
}

.book-cover {
  width: 100%;
  max-width: 350px;
  height: auto;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
}

.lead-form-card {
  background-color: var(--bg);
  border-radius: 12px;
  border: 1px solid var(--light);
}

.form-control {
  height: 50px;
  border-radius: 8px;
  border: 1px solid var(--light);
  padding: 10px 15px;
  font-size: 16px;
  color: var(--dark);
}

.form-control::placeholder {
  color: var(--muted);
}

.form-control:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 0.25rem rgba(40, 238, 252, 0.25);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: auto;
  max-width: 100%;
  padding: 14px 28px;
  margin: 8px 0;
  gap: 8px;
  border: none;
  border-radius: 10px;
  font-weight: 600;
  font-size: 16px;
  line-height: 1.2;
  text-align: center;
  text-decoration: none;
  white-space: nowrap;
  box-sizing: border-box;
  cursor: pointer;
  transition: filter 0.25s ease, box-shadow 0.25s ease, transform 0.25s ease;
  min-height: 44px; /* Minimum tap target height */
}

.btn-cta {
  background: var(--primary);
  color: var(--on-primary) !important;
  box-shadow: 0 6px 16px rgba(0,0,0,0.15);
}

.btn-secondary {
  background: var(--secondary);
  color: var(--on-secondary) !important;
}

.btn-cta:hover, .btn-secondary:hover {
  filter: brightness(0.92);
  box-shadow: 0 8px 20px rgba(0,0,0,0.20);
  transform: translateY(-1px);
}

section {
  padding: 70px 0;
}

.bg-surface {
  background-color: var(--surface);
}

.feature-card, .chapter-card {
  background-color: var(--bg);
  border-radius: 12px;
  border: 1px solid var(--light);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.feature-card:hover, .chapter-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.08);
}

.feature-card .card-title, .chapter-card .card-title {
  color: var(--dark);
}

.feature-card .card-text, .chapter-card p {
  color: var(--muted);
}

.list-group-item {
  background-color: transparent; /* Ensure chapter cards define their own bg */
  border: none;
  padding: 0;
}

.list-group-item:first-child {
  border-top-left-radius: 0;
  border-top-right-radius: 0;
}

.list-group-item:last-child {
  border-bottom-left-radius: 0;
  border-bottom-right-radius: 0;
}

.footer {
  background-color: var(--dark);
  color: #ffffff;
}

.footer small {
  color: rgba(255, 255, 255, 0.6);
}

/* Responsive adjustments */
@media (max-width: 991.98px) {
  .hero-section .text-lg-start {
    text-align: center !important;
  }
  .hero-section .mx-lg-0 {
    margin-left: auto !important;
    margin-right: auto !important;
  }
}

@media (max-width: 767.98px) {
  h1 {
    font-size: 2.5rem;
  }
  .book-cover {
    margin-top: 2rem;
  }
  section {
    padding: 40px 0;
  }
  .hero-section {
    padding-top: 40px;
    padding-bottom: 40px;
  }
  .btn {
    display: block;
    width: 100%;
  }
}

@media (max-width: 575.98px) {
  h1 {
    font-size: 2rem;
  }
  .lead-form-card {
    padding: 1.5rem;
  }
  .feature-card {
    padding: 1.5rem;
  }
  .chapter-card {
    padding: 1.5rem;
  }
}