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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: linear-gradient(180deg, #f5f7fa 0%, #eef2f5 100%);
  min-height: 100vh;
  padding: 40px 20px;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 920px;
  margin: 0 auto;
}

h1 {
  font-size: 34px;
  font-weight: 700;
  color: #1d1d1f;
  text-align: center;
  margin-bottom: 12px;
  letter-spacing: -0.5px;
}

h2 {
  font-size: 24px;
  font-weight: 600;
  color: #1d1d1f;
  text-align: center;
  margin-bottom: 28px;
  letter-spacing: -0.3px;
}

.nav-box {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin-bottom: 50px;
  flex-wrap: wrap;
}

.nav-box-item {
  padding: 12px 24px;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-radius: 20px;
  font-size: 15px;
  font-weight: 500;
  color: #007aff;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.25, 1, 0.5, 1);
  box-shadow: 0 4px 15px rgba(0, 122, 255, 0.08);
  border: 1px solid rgba(0, 122, 255, 0.1);
}

.nav-box-item:hover {
  background: #007aff;
  color: white;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(0, 122, 255, 0.25);
}

.catalog {
  display: flex;
  flex-direction: column;
  gap: 16px;
  align-items: center;
}

.catalog-item {
  width: 380px;
  padding: 18px 28px;
  background: rgba(255, 255, 255, 0.9);
  border-radius: 22px;
  text-align: center;
  font-size: 16px;
  font-weight: 500;
  color: #1d1d1f;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.25, 1, 0.5, 1);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.04);
  border: 1px solid rgba(0, 0, 0, 0.04);
}

.catalog-item:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.08);
  background: white;
  color: #007aff;
}

.top-back {
  font-size: 15px;
  font-weight: 500;
  color: #007aff;
  cursor: pointer;
  margin-bottom: 24px;
  display: inline-block;
  transition: all 0.2s ease;
}

.top-back:hover {
  transform: translateX(-3px);
  opacity: 0.8;
}

.demo-box {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(30px);
  -webkit-backdrop-filter: blur(30px);
  padding: 36px;
  border-radius: 28px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.08);
  text-align: center;
  border: 1px solid rgba(0, 0, 0, 0.04);
  margin-bottom: 30px;
}

canvas {
  border-radius: 20px;
  background: #fafbfc;
  box-shadow: inset 0 2px 8px rgba(0, 0, 0, 0.05);
  max-width: 100%;
}

input[type="range"] {
  width: 320px;
  height: 6px;
  border-radius: 3px;
  background: rgba(0, 122, 255, 0.1);
  outline: none;
  -webkit-appearance: none;
  margin-top: 20px;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #007aff;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(0, 122, 255, 0.3);
  transition: all 0.2s ease;
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.15);
  box-shadow: 0 6px 20px rgba(0, 122, 255, 0.4);
}

.text-box {
  background: rgba(255, 255, 255, 0.9);
  padding: 36px;
  border-radius: 28px;
  line-height: 1.7;
  font-size: 16px;
  color: #333336;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
  border: 1px solid rgba(0, 0, 0, 0.03);
}

.text-box h3 {
  font-size: 18px;
  font-weight: 600;
  color: #1d1d1f;
  margin-bottom: 12px;
  margin-top: 20px;
}

.text-box p {
  margin-bottom: 8px;
  color: #333336;
}

.page {
  display: block;
  animation: fadeIn 0.45s cubic-bezier(0.25, 1, 0.5, 1);
}

.hidden {
  display: none !important;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}