:root {
  --primary: #0a84ff;
  --primary-hover: #0070e0;
  --bg: #f5f7fa;
  --surface: #ffffff;
  --text: #1d1d1f;
  --text-muted: #86868b;
  --border: #e5e5ea;
  --radius: 16px;
}
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
html {
  scroll-behavior: smooth;
}
body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Helvetica Neue", Arial, sans-serif;
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a {
  text-decoration: none;
  color: var(--primary);
}
img {
  max-width: 100%;
  display: block;
  object-fit: cover;
}
.container {
  max-width: 1024px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
header {
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  z-index: 100;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.logo-group {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 20px;
  color: var(--text);
}
.logo-group img {
  height: 32px;
  width: auto;
  border-radius: 8px;
}
nav.desktop-nav {
  display: none;
}
nav.desktop-nav a {
  color: var(--text);
  font-size: 15px;
  margin-left: 24px;
  transition: color 0.2s;
}
nav.desktop-nav a:hover, nav.desktop-nav a.active {
  color: var(--primary);
}
.btn-download {
  background-color: var(--primary);
  color: #fff;
  padding: 8px 20px;
  border-radius: 99px;
  font-size: 14px;
  font-weight: 600;
  transition: background-color 0.2s;
  display: inline-block;
}
.btn-download:hover {
  background-color: var(--primary-hover);
  color: #fff;
}
.menu-toggle {
  display: block;
  background: none;
  border: none;
  font-size: 16px;
  color: var(--text);
  cursor: pointer;
  padding: 8px;
}
.mobile-nav {
  display: none;
  flex-direction: column;
  padding: 10px 20px 20px;
  background: #fff;
  border-bottom: 1px solid var(--border);
}
.mobile-nav.is-open {
  display: flex;
}
.mobile-nav a {
  color: var(--text);
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
  font-size: 15px;
}
.mobile-nav a:last-child {
  border-bottom: none;
}

/* Sections */
section {
  padding: 60px 0;
  scroll-margin-top: 70px;
}
.section-header {
  margin-bottom: 32px;
}
.section-header h2 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 8px;
}
.section-header p {
  color: var(--text-muted);
  font-size: 16px;
}

/* Hero */
.hero {
  background: #fff;
  padding: 40px 0 60px;
}
.hero h1 {
  font-size: 32px;
  line-height: 1.3;
  margin-bottom: 16px;
}
.hero p {
  font-size: 17px;
  color: var(--text-muted);
  margin-bottom: 32px;
  max-width: 600px;
}
.hero-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}
.hero-img-wrap {
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--border);
  position: relative;
  aspect-ratio: 16/9;
}
.hero-img-wrap img {
  width: 100%;
  height: 100%;
  transition: transform 0.4s;
}
.hero-img-wrap:hover img {
  transform: scale(1.02);
}

/* Quilt / Content Library */
.card-grid-3 {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}
.library-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}
.library-item {
  position: relative;
  border-radius: var(--radius);
  overflow: hidden;
  aspect-ratio: 3/4;
  background: #fff;
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}
.library-item img {
  width: 100%;
  height: 100%;
  transition: transform 0.3s;
}
.library-item:hover img {
  transform: scale(1.03);
}
.lib-tag {
  position: absolute;
  bottom: 12px;
  left: 12px;
  background: rgba(0,0,0,0.6);
  color: #fff;
  font-size: 12px;
  padding: 4px 10px;
  border-radius: 99px;
  backdrop-filter: blur(4px);
}

/* UI Preview */
.ui-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}
.ui-card {
  background: #fff;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 4px 16px rgba(0,0,0,0.06);
  border: 1px solid var(--border);
}
.ui-card img {
  width: 100%;
  aspect-ratio: 16/10;
}

/* After Download */
.after-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}
.after-card {
  background: #fff;
  border-radius: var(--radius);
  overflow: hidden;
}
.after-card img {
  width: 100%;
  aspect-ratio: 4/3;
}

/* Steps */
.steps-container {
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.step-item {
  display: flex;
  flex-direction: column;
  background: #fff;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 2px 10px rgba(0,0,0,0.04);
}
.step-img {
  position: relative;
  width: 100%;
  aspect-ratio: 16/9;
}
.step-img img {
  width: 100%;
  height: 100%;
}
.step-num {
  position: absolute;
  top: 12px;
  left: 12px;
  background: var(--primary);
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 99px;
}
.step-content {
  padding: 24px;
}
.step-content h3 {
  font-size: 18px;
  margin-bottom: 8px;
}
.step-content p {
  color: var(--text-muted);
  font-size: 15px;
}

/* Footer */
footer {
  background: #fff;
  border-top: 1px solid var(--border);
  padding: 40px 0;
  font-size: 13px;
  color: var(--text-muted);
  text-align: center;
}
.footer-content p {
  margin-bottom: 8px;
}
.footer-content a {
  color: var(--text-muted);
  text-decoration: underline;
  transition: color 0.2s;
}
.footer-content a:hover {
  color: var(--text);
}
.time-tag {
  font-size: 12px;
  color: #b0b0b5;
  margin-top: 12px;
}

/* Responsive */
@media (min-width: 768px) {
  .hero h1 { font-size: 42px; }
  .hero-grid { grid-template-columns: repeat(3, 1fr); }
  .hero-img-wrap:nth-child(1) { grid-column: span 2; aspect-ratio: 16/9; }
  .hero-img-wrap:nth-child(2), .hero-img-wrap:nth-child(3) { aspect-ratio: 3/4; }
  
  .library-grid { grid-template-columns: repeat(3, 1fr); }
  
  .ui-grid { grid-template-columns: repeat(2, 1fr); }
  .ui-card:first-child { grid-column: span 2; }
  .ui-card:first-child img { aspect-ratio: 21/9; }
  
  .after-grid { grid-template-columns: repeat(3, 1fr); }
  
  .steps-container { 
    display: grid; 
    grid-template-columns: repeat(2, 1fr); 
  }
}

@media (min-width: 1024px) {
  section { padding: 80px 0; }
  .header-inner { height: 70px; }
  .menu-toggle { display: none; }
  nav.desktop-nav { display: flex; align-items: center; }
  .logo-group img { height: 36px; }
  
  .hero { padding: 60px 0 80px; }
  .hero-grid { grid-template-columns: 2fr 1fr 1fr; }
  
  .library-grid { grid-template-columns: repeat(3, 1fr); }
  .library-item:nth-child(1), .library-item:nth-child(4) {
    grid-column: span 2;
    aspect-ratio: 16/9;
  }
  
  .steps-container { grid-template-columns: repeat(3, 1fr); }
}