:root {
    --bg-page: #F8FAFC;
    --bg-hero-start: #F0FDFA;
    --bg-hero-end: #F1F5F9;
    --bg-card: #FFFFFF;
    --primary-accent: #0D9488;
    --primary-accent-light: #CCFBF1;
    --text-dark: #1E293B;
    --text-medium: #475569;
    --text-light: #94A3B8;
    --border-color: #E2E8F0;
    --error-bg: #FEF2F2;
    --error-text: #DC2626;
    --warning-bg: #FFFBEB;
    --warning-text: #B45309;
    --success-bg: #ECFDF5;
    --success-text: #065F46;
    --disabled-bg: #F1F5F9;
    --disabled-text: #94A3B8;
  }
  
  * {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }
  
  html {
    scroll-behavior: smooth;
  }
  
  body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-page);
    color: var(--text-medium);
    line-height: 1.6;
    overflow-x: hidden;
  }
  
  h1, h2, h3, h4 {
    color: var(--text-dark);
    line-height: 1.2;
    font-weight: 600;
  }
  
  h1 {
    font-size: clamp(1.75rem, 5vw, 2.5rem);
    font-weight: 800;
    margin-bottom: 1rem;
  }
  
  h2.section-title {
    font-size: clamp(1.25rem, 4vw, 1.5rem);
    margin-bottom: 1.25rem;
  }
  
  h3.subsection-title {
    font-size: clamp(1rem, 3vw, 1.1rem);
    margin-bottom: 0.75rem;
  }
  
  /* Navigation */
  .navbar {
    background-color: var(--bg-card);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 1000;
    width: 100%;
  }
  
  .nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem clamp(0.75rem, 3vw, 1rem);
  }
  
  .nav-brand {
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }
  
  .nav-logo {
    height: 32px;
    width: auto;
  }
  
  .brand-name {
    font-weight: 700;
    color: var(--text-dark);
    font-size: 1.1rem;
  }
  
  /* Navigation Toggle */
  .nav-toggle {
    display: flex;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    gap: 0.25rem;
    z-index: 1002;
  }
  
  .nav-toggle span {
    width: 24px;
    height: 2px;
    background-color: var(--text-dark);
    transition: all 0.3s ease;
    transform-origin: center;
  }
  
  /* Navigation Slider */
  .nav-slider {
    position: fixed;
    top: 0;
    right: -100%;
    width: 300px;
    height: 100vh;
    background-color: var(--bg-card);
    box-shadow: -4px 0 20px rgba(0, 0, 0, 0.1);
    transition: right 0.3s ease-in-out;
    z-index: 1001;
    overflow-y: auto;
  }
  
  .nav-slider.active {
    right: 0;
  }
  
  .slider-content {
    padding: 1.5rem;
    height: 100%;
  }
  
  .slider-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
  }
  
  .slider-close {
    background: none;
    border: none;
    font-size: 1.25rem;
    color: var(--text-dark);
    cursor: pointer;
    padding: 0.5rem;
    z-index: 1002;
  }
  
  .slider-links {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
  }
  
  .slider-link {
    display: block;
    padding: 1rem;
    color: var(--text-dark);
    text-decoration: none;
    font-weight: 500;
    border-radius: 0.5rem;
    transition: all 0.2s;
  }
  
  .slider-link:hover, .slider-link.active {
    background-color: var(--primary-accent-light);
    color: var(--primary-accent);
  }
  
  /* Overlay when slider is open */
  .nav-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
  }
  
  .nav-overlay.active {
    opacity: 1;
    visibility: visible;
  }
  
  /* Hero Section */
  .hero-section {
    background: linear-gradient(135deg, var(--bg-hero-start) 0%, var(--bg-hero-end) 100%);
    padding: clamp(2rem, 6vw, 4rem) clamp(1rem, 4vw, 2rem);
    text-align: center;
    position: relative;
    overflow: hidden;
  }
  
  .hero-content {
    max-width: 800px;
    margin: 0 auto;
  }
  
  .hero-text p {
    font-size: clamp(1rem, 3vw, 1.25rem);
    margin-bottom: 2rem;
    color: var(--text-medium);
  }
  
  /* NEW: Overview Section */
  .overview-section {
    padding: 4rem 1rem;
    background-color: var(--bg-page);
  }
  
  .overview-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 2rem;
  }
  
  @media (min-width: 768px) {
    .overview-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  .overview-card {
    background: var(--bg-card);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
  }
  
  .overview-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
  }
  
  .overview-icon {
    width: 60px;
    height: 60px;
    background: var(--primary-accent-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
  }
  
  .overview-icon i {
    font-size: 1.5rem;
    color: var(--primary-accent);
  }
  
  .overview-card h3 {
    color: var(--text-dark);
    font-size: 1.2rem;
    margin-bottom: 1rem;
    font-weight: 600;
    line-height: 1.4;
  }
  
  .overview-card p {
    color: var(--text-medium);
    line-height: 1.6;
    font-size: 0.95rem;
  }
  
  /* NEW: Use Cases Section */
  .use-cases-section {
    padding: 4rem 1rem;
    background: linear-gradient(135deg, var(--bg-hero-start) 0%, var(--bg-hero-end) 100%);
  }
  
  .use-cases-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 2rem;
  }
  
  @media (min-width: 768px) {
    .use-cases-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  @media (min-width: 1024px) {
    .use-cases-grid {
      grid-template-columns: repeat(3, 1fr);
    }
  }
  
  .use-case-card {
    background: var(--bg-card);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
  }
  
  .use-case-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
  }
  
  .use-case-icon {
    width: 60px;
    height: 60px;
    background: var(--primary-accent-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
  }
  
  .use-case-icon i {
    font-size: 1.5rem;
    color: var(--primary-accent);
  }
  
  .use-case-card h3 {
    color: var(--text-dark);
    font-size: 1.2rem;
    margin-bottom: 1.5rem;
    font-weight: 600;
    line-height: 1.4;
  }
  
  .problem-solution {
    margin-bottom: 1.5rem;
  }
  
  .problem, .solution {
    margin-bottom: 1rem;
  }
  
  .problem h4, .solution h4 {
    font-size: 1rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
  }
  
  .problem h4 {
    color: var(--error-text);
  }
  
  .solution h4 {
    color: var(--success-text);
  }
  
  .problem p, .solution p {
    font-size: 0.9rem;
    line-height: 1.5;
    color: var(--text-medium);
  }
  
  .pro-tip {
    background-color: var(--warning-bg);
    border-left: 4px solid var(--warning-text);
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
  }
  
  .benefits h4 {
    font-size: 1rem;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
  }
  
  .benefits ul {
    padding-left: 1.5rem;
    font-size: 0.9rem;
  }
  
  .benefits li {
    margin-bottom: 0.5rem;
    line-height: 1.4;
  }
  
  /* NEW: Enhanced How-To Section */
  .enhanced-howto-section {
    padding: 4rem 1rem;
    background-color: var(--bg-page);
  }
  
  .enhanced-howto-steps {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    margin-top: 2rem;
  }
  
  .howto-step {
    display: flex;
    gap: 1.5rem;
    background: var(--bg-card);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    border: 1px solid var(--border-color);
  }
  
  .step-number {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background-color: var(--primary-accent);
    color: white;
    border-radius: 50%;
    font-weight: 700;
    font-size: 1.25rem;
    flex-shrink: 0;
  }
  
  .step-content {
    flex: 1;
  }
  
  .step-content h3 {
    color: var(--text-dark);
    font-size: 1.2rem;
    margin-bottom: 1rem;
    font-weight: 600;
  }
  
  .step-content p {
    color: var(--text-medium);
    line-height: 1.6;
    margin-bottom: 1.5rem;
  }
  
  .quick-tip {
    background-color: var(--primary-accent-light);
    border-left: 4px solid var(--primary-accent);
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
  }
  
  .troubleshooting h4 {
    font-size: 1rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
  }
  
  .troubleshooting p {
    font-size: 0.9rem;
    color: var(--text-medium);
    margin-bottom: 0;
  }
  
  /* NEW: Tips Section */
  .tips-section {
    padding: 4rem 1rem;
    background: linear-gradient(135deg, var(--bg-hero-start) 0%, var(--bg-hero-end) 100%);
  }
  
  .tips-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 2rem;
  }
  
  @media (min-width: 768px) {
    .tips-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  @media (min-width: 1024px) {
    .tips-grid {
      grid-template-columns: repeat(4, 1fr);
    }
  }
  
  .tip-card {
    background: var(--bg-card);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
  }
  
  .tip-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
  }
  
  .tip-number {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background-color: var(--primary-accent);
    color: white;
    border-radius: 50%;
    font-weight: 700;
    margin-bottom: 1rem;
  }
  
  .tip-card h3 {
    color: var(--text-dark);
    font-size: 1.1rem;
    margin-bottom: 1rem;
    font-weight: 600;
    line-height: 1.4;
  }
  
  .tip-card p {
    color: var(--text-medium);
    line-height: 1.6;
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
  }
  
  .optimal-settings, .pitfall-avoidance, .advanced-technique, .integration-advice {
    padding: 1rem;
    border-radius: 0.5rem;
    margin-top: 1rem;
  }
  
  .optimal-settings {
    background-color: var(--success-bg);
    border-left: 4px solid var(--success-text);
  }
  
  .pitfall-avoidance {
    background-color: var(--error-bg);
    border-left: 4px solid var(--error-text);
  }
  
  .advanced-technique {
    background-color: var(--primary-accent-light);
    border-left: 4px solid var(--primary-accent);
  }
  
  .integration-advice {
    background-color: var(--warning-bg);
    border-left: 4px solid var(--warning-text);
  }
  
  .optimal-settings h4, .pitfall-avoidance h4, .advanced-technique h4, .integration-advice h4 {
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
  }
  
  .optimal-settings p, .pitfall-avoidance p, .advanced-technique p, .integration-advice p {
    font-size: 0.85rem;
    margin-bottom: 0;
  }
  
  /* NEW: Why Choose Us Section */
  .why-choose-section {
    padding: 4rem 1rem;
    background-color: var(--bg-page);
  }
  
  .advantages-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 2rem;
  }
  
  @media (min-width: 768px) {
    .advantages-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  @media (min-width: 1024px) {
    .advantages-grid {
      grid-template-columns: repeat(3, 1fr);
    }
  }
  
  .advantage-card {
    background: var(--bg-card);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
    text-align: center;
  }
  
  .advantage-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
  }
  
  .advantage-icon {
    width: 80px;
    height: 80px;
    background: var(--primary-accent-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
  }
  
  .advantage-icon i {
    font-size: 2rem;
    color: var(--primary-accent);
  }
  
  .advantage-card h3 {
    color: var(--text-dark);
    font-size: 1.2rem;
    margin-bottom: 1rem;
    font-weight: 600;
    line-height: 1.4;
  }
  
  .advantage-card p {
    color: var(--text-medium);
    line-height: 1.6;
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
  }
  
  .advantage-metrics {
    display: flex;
    justify-content: center;
  }
  
  .metric {
    text-align: center;
  }
  
  .metric-value {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-accent);
    line-height: 1;
  }
  
  .metric-label {
    font-size: 0.8rem;
    color: var(--text-light);
  }
  
  /* NEW: Success Stories Section */
  .success-stories-section {
    padding: 4rem 1rem;
    background: linear-gradient(135deg, var(--bg-hero-start) 0%, var(--bg-hero-end) 100%);
  }
  
  .stories-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 2rem;
  }
  
  @media (min-width: 768px) {
    .stories-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  @media (min-width: 1024px) {
    .stories-grid {
      grid-template-columns: repeat(3, 1fr);
    }
  }
  
  .story-card {
    background: var(--bg-card);
    border-radius: 1rem;
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
  }
  
  .story-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
  }
  
  .story-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.5rem;
    background-color: var(--primary-accent-light);
  }
  
  .user-avatar {
    width: 50px;
    height: 50px;
    background-color: var(--primary-accent);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.25rem;
  }
  
  .user-info h3 {
    color: var(--text-dark);
    font-size: 1.1rem;
    margin-bottom: 0.25rem;
  }
  
  .user-info p {
    color: var(--text-medium);
    font-size: 0.85rem;
  }
  
  .story-content {
    padding: 1.5rem;
  }
  
  .before-after {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1.5rem;
  }
  
  .before h4, .after h4 {
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
  }
  
  .before h4 {
    color: var(--error-text);
  }
  
  .after h4 {
    color: var(--success-text);
  }
  
  .before p, .after p {
    font-size: 0.85rem;
    line-height: 1.5;
    color: var(--text-medium);
  }
  
  .results h4 {
    font-size: 1rem;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
  }
  
  .results ul {
    padding-left: 1.5rem;
    font-size: 0.85rem;
    margin-bottom: 1.5rem;
  }
  
  .results li {
    margin-bottom: 0.5rem;
    line-height: 1.4;
  }
  
  .testimonial blockquote {
    font-style: italic;
    color: var(--text-medium);
    border-left: 4px solid var(--primary-accent);
    padding-left: 1rem;
    margin: 0;
    font-size: 0.9rem;
  }
  
  /* NEW: Technical Section */
  .technical-section {
    padding: 4rem 1rem;
    background-color: var(--bg-page);
  }
  
  .technical-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 2rem;
  }
  
  @media (min-width: 768px) {
    .technical-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  .technical-card {
    background: var(--bg-card);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    border: 1px solid var(--border-color);
  }
  
  .technical-card h3 {
    color: var(--text-dark);
    font-size: 1.2rem;
    margin-bottom: 1rem;
    font-weight: 600;
    line-height: 1.4;
  }
  
  .technical-card p {
    color: var(--text-medium);
    line-height: 1.6;
    font-size: 0.95rem;
    margin-bottom: 1rem;
  }
  
  .technical-note {
    background-color: var(--primary-accent-light);
    border-radius: 0.5rem;
    padding: 1rem;
    margin-top: 1.5rem;
  }
  
  .technical-note h4 {
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
  }
  
  .technical-note p {
    font-size: 0.85rem;
    margin-bottom: 0;
  }
  
  /* NEW: Enhanced FAQ Section */
  .enhanced-faq-section {
    padding: 4rem 1rem;
    background: linear-gradient(135deg, var(--bg-hero-start) 0%, var(--bg-hero-end) 100%);
  }
  
  .enhanced-faq-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 2rem;
  }
  
  @media (min-width: 768px) {
    .enhanced-faq-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  .enhanced-faq-item {
    background: var(--bg-card);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    border: 1px solid var(--border-color);
  }
  
  .enhanced-faq-item h3 {
    color: var(--primary-accent);
    font-size: 1.1rem;
    margin-bottom: 1rem;
    font-weight: 600;
    line-height: 1.4;
  }
  
  .enhanced-faq-item p {
    color: var(--text-medium);
    line-height: 1.6;
    font-size: 0.95rem;
    margin-bottom: 1rem;
  }
  
  /* Cards */
  .card {
    background-color: var(--bg-card);
    border-radius: 1rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    padding: clamp(1.5rem, 4vw, 2rem);
    margin-bottom: 1.5rem;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  
  .card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
  }
  
  .main-card {
    margin-top: 2rem !important;
    position: relative;
    z-index: 10;
  }
  
  /* Centered Form Container */
  .centered-form-container {
    max-width: 800px;
    margin: 0 auto;
    width: 100%;
  }
  
  /* Form Elements */
  .form-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }
  
  .input-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
  }
  
  .input-group label {
    font-weight: 500;
    color: var(--text-dark);
  }
  
  .input-group input, .input-group select, .input-group textarea {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    transition: all 0.2s;
    background-color: white;
    font-family: 'Inter', sans-serif;
  }
  
  .input-group input:focus, .input-group select:focus, .input-group textarea:focus {
    outline: none;
    border-color: var(--primary-accent);
    box-shadow: 0 0 0 3px rgba(13, 148, 136, 0.1);
  }
  
  .input-help {
    font-size: 0.875rem;
    color: var(--text-light);
  }
  
  .deck-selection {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
  }
  
  .input-with-button {
    display: flex;
    gap: 0.5rem;
  }
  
  .input-with-button input {
    flex: 1;
  }
  
  /* Buttons */
  .calculate-button {
    background-color: var(--primary-accent);
    color: white;
    border: none;
    padding: 1rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s;
    text-align: center;
    width: 100%;
    margin: 2rem 0 !important;
  }
  
  .calculate-button:hover {
    background-color: #0f766e;
    transform: translateY(-2px);
  }
  
  .calculate-button:disabled {
    background-color: var(--disabled-bg);
    color: var(--disabled-text);
    cursor: not-allowed;
    transform: none;
  }
  
  .cta-button {
    display: inline-block;
    background-color: var(--primary-accent);
    color: white;
    padding: 1rem 2rem;
    border-radius: 0.5rem;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.2s;
    border: none;
    cursor: pointer;
  }
  
  .cta-button:hover {
    background-color: #0f766e;
    transform: translateY(-2px);
  }
  
  .action-button {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background-color: white;
    color: var(--text-dark);
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.875rem;
    text-align: center;
  }
  
  .action-button:hover:not(:disabled) {
    border-color: var(--primary-accent);
    color: var(--primary-accent);
  }
  
  .action-button:disabled {
    background-color: var(--disabled-bg);
    color: var(--disabled-text);
    cursor: not-allowed;
    border-color: var(--border-color);
  }
  
  .action-button.secondary {
    background-color: var(--bg-page);
  }
  
  .action-button.danger {
    color: var(--error-text);
    border-color: var(--error-text);
  }
  
  .action-button.danger:hover:not(:disabled) {
    background-color: var(--error-bg);
  }
  
  /* Study Section */
  .study-area {
    margin-top: 1.5rem;
  }
  
  .flashcard-study {
    perspective: 1000px;
    width: 100%;
    height: 300px;
    margin-bottom: 1.5rem;
  }
  
  .flashcard-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.6s;
    transform-style: preserve-3d;
    cursor: pointer;
  }
  
  .flashcard-study.flipped .flashcard-inner {
    transform: rotateY(180deg);
  }
  
  .flashcard-front, .flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  }
  
  .flashcard-front {
    background-color: white;
    color: var(--text-dark);
    border: 1px solid var(--border-color);
  }
  
  .flashcard-back {
    background-color: var(--primary-accent);
    color: white;
    transform: rotateY(180deg);
  }
  
  .card-content {
    font-size: 1.25rem;
    line-height: 1.6;
    max-height: 100%;
    overflow-y: auto;
    width: 100%;
    word-wrap: break-word;
  }
  
  .flip-hint {
    position: absolute;
    bottom: 1rem;
    font-size: 0.875rem;
    color: var(--text-light);
  }
  
  .flashcard-back .flip-hint {
    color: rgba(255, 255, 255, 0.8);
  }
  
  .study-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
  }
  
  .study-progress {
    font-weight: 500;
    color: var(--text-dark);
  }
  
  .card-rating {
    text-align: center;
  }
  
  .card-rating h4 {
    margin-bottom: 1rem;
    color: var(--text-dark);
  }
  
  .rating-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.5rem;
  }
  
  .rating-button {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background-color: white;
    color: var(--text-dark);
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.875rem;
  }
  
  .rating-button:hover:not(:disabled) {
    border-color: var(--primary-accent);
    color: var(--primary-accent);
  }
  
  .rating-button:disabled {
    background-color: var(--disabled-bg);
    color: var(--disabled-text);
    cursor: not-allowed;
  }
  
  .rating-button[data-rating="again"]:hover:not(:disabled) {
    border-color: var(--error-text);
    color: var(--error-text);
  }
  
  .rating-button[data-rating="easy"]:hover:not(:disabled) {
    border-color: var(--success-text);
    color: var(--success-text);
  }
  
  /* Flashcard Management */
  .flashcards-list {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
    margin-bottom: 1.5rem;
    max-height: 400px;
    overflow-y: auto;
    padding: 1rem;
    background-color: var(--bg-page);
    border-radius: 0.5rem;
    border: 1px solid var(--border-color);
  }
  
  .flashcard-item {
    background-color: white;
    border-radius: 0.75rem;
    padding: 1.25rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    border: 1px solid var(--border-color);
    transition: all 0.2s;
  }
  
  .flashcard-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  }
  
  .flashcard-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 0.75rem;
  }
  
  .flashcard-content {
    margin-bottom: 1rem;
    flex: 1;
  }
  
  .flashcard-front-preview, .flashcard-back-preview {
    margin-bottom: 0.5rem;
  }
  
  .flashcard-front-preview h4, .flashcard-back-preview h4 {
    font-size: 0.875rem;
    color: var(--text-light);
    margin-bottom: 0.25rem;
  }
  
  .flashcard-front-preview p, .flashcard-back-preview p {
    font-size: 0.95rem;
    color: var(--text-dark);
    line-height: 1.4;
    word-wrap: break-word;
  }
  
  .flashcard-actions {
    display: flex;
    gap: 0.5rem;
    flex-shrink: 0;
  }
  
  .management-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
  }
  
  /* Empty States */
  .empty-state {
    text-align: center;
    padding: 3rem 2rem;
    color: var(--text-light);
  }
  
  .empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--border-color);
  }
  
  .empty-state h3 {
    color: var(--text-light);
    margin-bottom: 0.5rem;
  }
  
  /* Message Boxes */
  .message-box {
    padding: 1rem;
    border-radius: 0.5rem;
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    margin-bottom: 1rem;
  }
  
  .message-box i {
    font-size: 1.25rem;
    margin-top: 0.125rem;
  }
  
  .message-content {
    flex: 1;
  }
  
  .message-content h4 {
    margin-bottom: 0.25rem;
    font-size: 1rem;
  }
  
  .error-box {
    background-color: var(--error-bg);
    color: var(--error-text);
    border-left: 4px solid var(--error-text);
  }
  
  .success-box {
    background-color: var(--success-bg);
    color: var(--success-text);
    border-left: 4px solid var(--success-text);
  }
  
  /* Animations */
  .animate-on-load {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.6s ease forwards;
  }
  
  @keyframes fadeInUp {
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }
  
  /* How-To Section */
  .how-to-section {
    padding: 4rem 1rem;
    background-color: var(--bg-page);
  }
  
  .how-to-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 2rem;
  }
  
  @media (min-width: 768px) {
    .how-to-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  @media (min-width: 1024px) {
    .how-to-grid {
      grid-template-columns: repeat(3, 1fr);
    }
  }
  
  .how-to-card {
    background: var(--bg-card);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
  }
  
  .how-to-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
  }
  
  .how-to-icon {
    width: 60px;
    height: 60px;
    background: var(--primary-accent-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
  }
  
  .how-to-icon i {
    font-size: 1.5rem;
    color: var(--primary-accent);
  }
  
  .how-to-card h3 {
    color: var(--text-dark);
    font-size: 1.2rem;
    margin-bottom: 1rem;
    font-weight: 600;
    line-height: 1.4;
  }
  
  .how-to-card p {
    color: var(--text-medium);
    line-height: 1.6;
    font-size: 0.95rem;
    margin-bottom: 1rem;
  }
  
  /* Content Sections */
  .content-section {
    padding: 3rem 1rem;
  }
  
  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
  }
  
  .section-subtitle {
    text-align: center;
    color: var(--text-medium);
    margin-bottom: 2rem;
    font-size: 1.1rem;
  }
  
  /* FAQ Section */
  .faq-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
    margin-top: 2rem;
  }
  
  @media (min-width: 768px) {
    .faq-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  .faq-item {
    background: var(--bg-card);
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
  }
  
  .faq-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
  }
  
  .faq-item h3 {
    color: var(--primary-accent);
    font-size: 1.1rem;
    margin-bottom: 0.75rem;
    font-weight: 600;
    line-height: 1.4;
  }
  
  .faq-item p {
    color: var(--text-medium);
    line-height: 1.6;
    font-size: 0.95rem;
  }
  
  /* Footer */
  .footer {
    background-color: var(--bg-card);
    padding: 2rem 1rem;
    margin-top: 4rem;
    text-align: center;
    border-top: 1px solid var(--border-color);
  }
  
  .footer-content {
    max-width: 800px;
    margin: 0 auto;
  }
  
  .footer-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin: 1rem 0;
  }
  
  .footer-links a {
    color: var(--text-medium);
    text-decoration: none;
    transition: color 0.2s;
  }
  
  .footer-links a:hover {
    color: var(--primary-accent);
  }
  
  .disclaimer {
    font-size: 0.875rem;
    color: var(--text-light);
    margin-top: 1rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
  }
  
  /* Privacy Notice */
  .privacy-notice {
    padding: 1rem;
    border-radius: 0.5rem;
    margin-top: 1rem;
    background-color: var(--success-bg);
    border-left: 4px solid var(--success-text);
  }
  
  .privacy-title {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
  }
  
  .privacy-text {
    font-size: 0.875rem;
    color: var(--text-medium);
  }
  
  /* Responsive Adjustments */
  @media (max-width: 767px) {
    .deck-selection {
      grid-template-columns: 1fr;
    }
    
    .study-controls {
      flex-direction: column;
      gap: 1rem;
    }
    
    .rating-buttons {
      grid-template-columns: repeat(2, 1fr);
    }
    
    .management-actions {
      flex-direction: column;
    }
    
    .input-with-button {
      flex-direction: column;
    }
    
    .flashcard-header {
      flex-direction: column;
      gap: 0.5rem;
    }
    
    .flashcard-actions {
      width: 100%;
      justify-content: flex-end;
    }
    
    .howto-step {
      flex-direction: column;
    }
    
    .step-number {
      align-self: flex-start;
    }
    
    .before-after {
      grid-template-columns: 1fr;
    }
  }
  
  @media (max-width: 480px) {
    .footer-links {
      flex-direction: column;
      gap: 0.5rem;
    }
    
    .card-content {
      font-size: 1rem;
    }
    
    .flashcard-front, .flashcard-back {
      padding: 1.5rem;
    }
    
    .rating-buttons {
      grid-template-columns: 1fr;
    }
    
    .tips-grid {
      grid-template-columns: 1fr;
    }
  }