:root {
    --primary-color: #1e293b;     /* Deep slate for header and accents */
    --secondary-color: #3b82f6;   /* Modern blue for highlights */
    --background-color: #f8fafc; /* Light, clean background */
    --surface-color: #ffffff;     /* Card and content surfaces */
    --text-color: #1e293b;        /* Rich dark text */
    --text-muted: #64748b;        /* Subtle muted text */
    --border-color: #e2e8f0;      /* Soft borders */
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
    --radius: 0.75rem;            /* Modern rounded corners */
}
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    margin: 0;
    background-color: var(--background-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    line-height: 1.6;
    padding-top: 3rem;
}
header {
    background-color: var(--primary-color);
    color: white;
    padding: 1.5rem 1rem;
    text-align: center;
    box-shadow: var(--shadow-md);
}
header h1 {
    margin: 0;
    font-size: 1.5rem;
    font-weight: 600;
}
main {
    flex-grow: 1;
    padding: 1.5rem;
    overflow-y: auto;
}
nav {
    display: flex;
    justify-content: space-around;
    background-color: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: 0.75rem 0;
    position: sticky;
    bottom: 0;
    box-shadow: var(--shadow-sm);
}
nav button {
    background: none;
    border: none;
    font-size: 1rem;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.75rem 1rem;
    transition: color 0.2s ease;
    font-weight: 500;
}
nav button.active {
    color: var(--secondary-color);
    position: relative;
}
nav button.active::after {
    content: '';
    position: absolute;
    bottom: -0.75rem;
    left: 50%;
    transform: translateX(-50%);
    width: 2rem;
    height: 3px;
    background-color: var(--secondary-color);
    border-radius: 2px;
}
.view {
    display: none;
}
.view.active {
    display: block;
}
.toc-list, .resources-list {
    list-style: none;
    padding: 0;
    margin: 0;
}
.toc-list li, .resources-list li {
    background-color: var(--surface-color);
    margin-bottom: 1rem;
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.toc-list li:hover, .resources-list li:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}
.toc-list li a, .resources-list a {
    display: block;
    padding: 1.25rem;
    text-decoration: none;
    color: inherit;
    transition: background-color 0.2s ease;
}
.toc-list li a:hover, .resources-list a:hover {
    background-color: #f1f5f9;
}
.catechism-content {
    background-color: var(--surface-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
}
.catechism-content h2 {
    color: var(--primary-color);
    margin-top: 0;
    font-size: 1.5rem;
    font-weight: 600;
}
.catechism-content .answer {
    background-color: #eff6ff;
    padding: 1.25rem;
    border-radius: var(--radius);
    border-left: 5px solid var(--secondary-color);
    margin: 1.5rem 0;
    font-style: normal;
    font-size: 1.1rem;
}
.catechism-content .scripture {
    font-weight: 600;
    color: var(--secondary-color);
    margin: 1.5rem 0 0.5rem;
    font-size: 1.05rem;
}
.catechism-content .other-scriptures {
    color: var(--text-muted);
    font-style: italic;
    margin: 0.5rem 0 1.5rem;
}
.catechism-content .explanation {
    margin-top: 1.5rem;
    color: var(--text-color);
}
.explanation-divider {
    margin: 2rem 0 1.5rem;
    border: none;
    border-top: 1px solid var(--border-color);
}
.expanded-explanation h4 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}
.expanded-explanation p {
    line-height: 1.7;
    margin-bottom: 1rem;
}.expanded-explanation {
    background-color: #f9fafb;
    padding: 1rem;
    border-left: 4px solid var(--secondary-color);
    border-radius: 4px;
}.welcome-content {
    text-align: center;
    padding: 3rem 1.5rem;
    max-width: 800px;
    margin: 0 auto;
}
.welcome-content h2 {
    color: var(--primary-color);
    font-size: 2rem;
    margin-bottom: 1.5rem;
}
.back-button {
    background: none;
    border: none;
    color: var(--secondary-color);
    font-size: 1.1rem;
    cursor: pointer;
    padding: 0.75rem 0;
    margin-bottom: 1.5rem;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}
.back-button::before {
    content: '←';
}
.back-button:hover {
    text-decoration: underline;
}
.resource-category {
    color: var(--primary-color);
    font-weight: 600;
    font-size: 1.2rem;
    margin: 2rem 0 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 3px solid var(--secondary-color);
}
.resources-list {
    margin-bottom: 2rem;
}
/* Mobile improvements */
@media (max-width: 640px) {
    main {
        padding: 1rem;
    }
    
    .catechism-content {
        padding: 1.25rem;
    }
    
    nav button {
        font-size: 0.9rem;
        padding: 0.5rem;
    }
}
.support-section {
    margin-top: 2.5rem;
    padding: 1.2rem;
    background-color: #e8f6f3;
    border-left: 4px solid var(--secondary-color);
    border-radius: 6px;
    text-align: center;
}

.support-section h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

#donate-btn {
    margin-top: 0.8rem;
    background-color: var(--secondary-color);
    color: white;
    border: none;
    padding: 0.7rem 1.4rem;
    font-size: 1rem;
    cursor: pointer;
    border-radius: 5px;
}

#donate-btn:hover {
    background-color: #2980b9;
}

#update-banner {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;

  display: flex;
  justify-content: space-between;
  align-items: center;

  padding: 0.75rem 1rem;
  background-color: #f59e0b;
  color: #000;
  font-weight: 600;

  box-shadow: 0 2px 6px rgba(0,0,0,0.2);
}

#update-banner button {
  background-color: #000;
  color: #fff;
  border: none;
  padding: 0.4rem 0.75rem;
  border-radius: 4px;
  cursor: pointer;
}

#update-banner button:hover {
  background-color: #333;
}

.scripture-notice {
    margin-top: 3rem;
    font-size: 0.75rem;
    color: #666;
    line-height: 1.4;
    text-align: center;
}

.print-btn {
  margin: 0.5rem 1rem 1rem;
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
  background-color: var(--secondary-color);
  color: #fff;
  border: none;
  border-radius: 5px;
  cursor: pointer;
}

.print-btn:hover {
  background-color: #2563eb;
}

iframe {
  width: 100%;
  height: calc(100vh - 150px); /* adjust to leave room for header/nav */
  border: none;
  border-radius: var(--radius);
}