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

body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: linear-gradient(135deg, #F8F9FA 0%, #E9ECEF 100%);
  min-height: 100vh;
  overflow-x: hidden;
  color: #212529;
}

/* Navigation */
header nav {
  background: white;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
  padding: 20px 40px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.top-menu {
  background-color: white;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
  padding: 20px 40px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
}

.app-title {
  font-size: 1.375rem;
  font-weight: bold;
  color: #212529;
  cursor: pointer;
  text-decoration: none;
}

.menu-items {
  display: flex;
  gap: 20px;
  align-items: center;
}

.menu-item {
  padding: 8px 12px;
  color: #495057;
  text-decoration: none;
  font-size: 1.125rem;
  border-radius: 8px;
  transition: all 0.2s ease;
  cursor: pointer;
}

.menu-item:hover {
  background-color: rgba(77, 171, 247, 0.1);
  color: #4DABF7;
}

.menu-item.active {
  color: #4DABF7;
  font-weight: bold;
}

/* Breadcrumbs */
.breadcrumbs {
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(4px);
  padding: 12px 40px;
  border-top: 1px solid rgba(0, 0, 0, 0.05);
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.breadcrumbs__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.breadcrumbs__item {
  display: inline-flex;
  align-items: center;
  font-size: 0.95rem;
  color: #495057;
}

.breadcrumbs__item + .breadcrumbs__item::before {
  content: "›";
  margin: 0 10px;
  color: #ADB5BD;
}

.breadcrumbs__link {
  color: #4DABF7;
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s ease, text-decoration 0.2s ease;
}

.breadcrumbs__link[aria-current="page"] {
  color: #1C7ED6;
  font-weight: 600;
}

.breadcrumbs__link:hover {
  text-decoration: underline;
  color: #1C7ED6;
}

@media (max-width: 768px) {
  .breadcrumbs {
    padding: 12px 20px;
  }

  .breadcrumbs__item {
    font-size: 0.9rem;
  }
}

/* Sections */
.section {
  padding: 60px 40px;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
}

/* Hero Section */
.hero {
  display: flex;
  align-items: center;
  gap: 50px;
  text-align: center;
}

.hero-section {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.app-logo {
  width: 120px;
  height: 120px;
  margin-bottom: 30px;
  border-radius: 25px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.hero-title {
  font-size: 2.5rem;
  font-weight: bold;
  color: #212529;
  margin-bottom: 20px;
  line-height: 1.2;
}

.hero-description {
  font-size: 1.125rem;
  color: #495057;
  line-height: 1.6;
  margin-bottom: 40px;
  max-width: 600px;
}

/* Buttons */
button {
  padding: 10px 20px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-size: 14px;
  transition: all 0.2s;
}

.btn-primary {
  background: #4DABF7;
  color: white;
  padding: 16px 48px;
  font-size: 1.125rem;
  font-weight: 600;
}

.btn-secondary {
  background: rgba(77,171,247,0.3);
  color: #4DABF7;
}

.btn-primary:hover, .btn-secondary:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(77,171,247,0.3);
}

.btn-active {
  background: #4DABF7;
  color: white;
}

/* Tone Generator */
.tone-generator {
  background: rgba(255,255,255,0.5);
  border-radius: 12px;
  padding: 30px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  max-width: 600px;
  margin: 0 auto;
}

.frequency-display {
  font-size: 2rem;
  color: #4DABF7;
  font-weight: bold;
  text-align: center;
  margin-bottom: 20px;
}

.controls {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.wave-buttons, .frequency-buttons, .preset-buttons {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
}

.volume-control {
  display: flex;
  align-items: center;
  gap: 10px;
}

.volume-slider {
  flex: 1;
  height: 6px;
  background: rgba(77,171,247,0.3);
  border-radius: 3px;
  outline: none;
}

.playback-controls {
  display: flex;
  gap: 20px;
  justify-content: center;
}

.play-btn {
  font-size: 24px;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: #4DABF7;
  color: white;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  margin: 0;
  line-height: 1;
  font-family: inherit;
}

/* How It Works */
.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 30px;
  margin-top: 40px;
}

.step-card {
  background: white;
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  text-align: center;
}

.step-icon {
  font-size: 48px;
  margin-bottom: 20px;
}

.step-title {
  font-size: 1.25rem;
  font-weight: bold;
  margin-bottom: 10px;
  color: #212529;
}

.step-desc {
  color: #495057;
  line-height: 1.6;
}

/* Testimonials */
.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
  margin-top: 40px;
}

.testimonial-card {
  background: rgba(255,255,255,0.8);
  padding: 25px;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}

.stars {
  color: #FFD700;
  margin-bottom: 15px;
}

.testimonial-quote {
  font-style: italic;
  color: #495057;
  margin-bottom: 15px;
  line-height: 1.6;
}

.testimonial-author {
  color: #4DABF7;
  font-weight: bold;
}

/* Blog */
.blog-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
  margin-top: 40px;
}

.blog-card {
  background: white;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  cursor: pointer;
  transition: transform 0.2s;
  position: relative;
}

.blog-card:hover {
  transform: translateY(-5px);
}

.blog-card-latest {
  border: 2px solid #4DABF7;
  box-shadow: 0 4px 25px rgba(77, 171, 247, 0.3);
  background: linear-gradient(135deg, #ffffff 0%, #f8fbff 100%);
}

.blog-card-latest:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 30px rgba(77, 171, 247, 0.4);
}

.blog-card-badge {
  position: absolute;
  top: 12px;
  right: 12px;
  background: linear-gradient(135deg, #4DABF7 0%, #339af0 100%);
  color: white;
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: bold;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  z-index: 10;
  box-shadow: 0 2px 8px rgba(77, 171, 247, 0.4);
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% {
    box-shadow: 0 2px 8px rgba(77, 171, 247, 0.4);
  }
  50% {
    box-shadow: 0 2px 12px rgba(77, 171, 247, 0.6);
  }
}

.blog-card img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.blog-card-content {
  padding: 20px;
}

.blog-card-title {
  font-size: 1.25rem;
  font-weight: bold;
  margin-bottom: 10px;
  color: #212529;
}

.blog-card-excerpt {
  color: #495057;
  line-height: 1.6;
}

.blog-card-date {
  margin-top: 12px;
  font-size: 0.875rem;
  color: #868e96;
  font-weight: 500;
}

/* FAQ Section */
.faq-section {
  margin-top: 60px;
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-item {
  background: white;
  border-radius: 12px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  overflow: hidden;
  transition: box-shadow 0.3s ease;
}

.faq-item:hover {
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.faq-question {
  padding: 20px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  font-size: 1.1rem;
  color: #212529;
  user-select: none;
}

.faq-icon {
  font-size: 0.8rem;
  transition: transform 0.3s ease;
  color: #4DABF7;
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease, padding 0.3s ease;
  padding: 0 20px;
  color: #495057;
  line-height: 1.6;
}

.faq-item.active .faq-answer {
  max-height: 500px;
  padding: 0 20px 20px 20px;
}

/* Related Posts */
.related-posts {
  margin-top: 60px;
  padding-top: 40px;
  border-top: 2px solid #E9ECEF;
}

.related-posts-title {
  font-size: 1.5rem;
  font-weight: bold;
  margin-bottom: 30px;
  color: #212529;
}

.related-posts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

/* Lazy Loading Images */
img[loading="lazy"] {
  opacity: 1;
  transition: opacity 0.3s;
}

/* Section Titles */
.section-title {
  font-size: 2rem;
  font-weight: bold;
  text-align: center;
  margin-bottom: 10px;
  color: #212529;
}

.section-subtitle {
  text-align: center;
  color: #495057;
  margin-bottom: 40px;
}

/* Footer */
footer {
  background: #F8F9FA;
  padding: 30px;
  text-align: center;
  color: #495057;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 20px;
  margin-bottom: 10px;
}

.footer-link {
  color: #495057;
  text-decoration: none;
}

.footer-link:hover {
  color: #4DABF7;
}

/* Page routing */
.page {
  display: none;
}

.page.active {
  display: block;
}

/* Store buttons */
.store-buttons {
  display: flex;
  gap: 16px;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  margin-top: 20px;
}

.store-button {
  height: 50px;
  cursor: pointer;
  transition: transform 0.2s ease;
  border: none;
  background: none;
  padding: 0;
}

.store-button:hover {
  transform: translateY(-2px);
}

.store-button img {
  height: 100%;
  width: auto;
}

/* Responsive */
@media (max-width: 768px) {
  header nav,
  .top-menu {
    padding: 20px;
    flex-direction: column;
    gap: 20px;
  }
  
  .hero {
    flex-direction: column;
  }
  
  .hero-title {
    font-size: 2rem;
  }
  
  .section {
    padding: 40px 20px;
  }
  
  .store-buttons {
    gap: 12px;
  }
}