:root {
  --bg: #121212;
  --surface: #1c1c1c;
  --surface-hover: #2a2a2a;
  --primary: #e53935;
  --primary-hover: #d32f2f;
  --text-main: #f5f5f5;
  --text-muted: #aaaaaa;
  --border: #333333;
  --radius: 12px;
  --font: -apple-system, BlinkMacSystemFont, "PingFang SC", "Helvetica Neue", Arial, sans-serif;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: var(--font);
  background-color: var(--bg);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { text-decoration: none; color: inherit; }
img { max-width: 100%; display: block; object-fit: cover; }
.container { width: 100%; max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* Header */
header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(18, 18, 18, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex; justify-content: space-between; align-items: center;
  height: 64px;
}
.logo-box { display: flex; align-items: center; gap: 10px; font-size: 20px; font-weight: bold; }
.logo-box img { height: 32px; width: auto; border-radius: 6px; }
.btn-download {
  background: var(--primary); color: #fff;
  padding: 8px 20px; border-radius: 20px;
  font-size: 15px; font-weight: bold;
  transition: background 0.3s;
}
.btn-download:hover { background: var(--primary-hover); }

/* Hero */
.hero { padding: 80px 0 60px; text-align: center; }
.hero h1 { font-size: 40px; line-height: 1.2; margin-bottom: 20px; font-weight: 800; }
.hero p { color: var(--text-muted); font-size: 16px; max-width: 600px; margin: 0 auto 30px; }
.hero .btn-download { display: inline-block; padding: 12px 36px; font-size: 18px; border-radius: 24px; }

/* Sections */
section { padding: 60px 0; }
.section-title { font-size: 28px; font-weight: bold; margin-bottom: 30px; text-align: center; }
.section-title span { color: var(--primary); }
.grid-2 { display: grid; grid-template-columns: 1fr; gap: 20px; }
.grid-3 { display: grid; grid-template-columns: 1fr; gap: 20px; }
.grid-4 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 15px; }

/* Cards */
.card {
  background: var(--surface); border-radius: var(--radius);
  overflow: hidden; border: 1px solid var(--border);
  transition: transform 0.2s, border-color 0.2s;
}
.card:hover { transform: translateY(-4px); border-color: var(--primary); }
.card img { width: 100%; height: auto; aspect-ratio: 3/4; }
.card-content { padding: 15px; }
.card-content h3 { font-size: 16px; margin-bottom: 8px; }
.card-content p { font-size: 13px; color: var(--text-muted); }

/* Features */
.feature-list { display: grid; gap: 20px; }
.feature-item {
  background: var(--surface); padding: 24px;
  border-radius: var(--radius); border: 1px solid var(--border);
}
.feature-item h3 { font-size: 18px; margin-bottom: 10px; color: #fff; }
.feature-item p { font-size: 14px; color: var(--text-muted); }

/* Steps */
.step-list { display: grid; gap: 20px; }
.step-box {
  display: flex; align-items: flex-start; gap: 15px;
  background: var(--surface); padding: 20px;
  border-radius: var(--radius);
}
.step-num {
  background: var(--primary); color: #fff;
  width: 32px; height: 32px; flex-shrink: 0;
  border-radius: 50%; display: flex; align-items: center; justify-content: center;
  font-weight: bold; font-size: 16px;
}
.step-box h3 { font-size: 16px; margin-bottom: 5px; }
.step-box p { font-size: 14px; color: var(--text-muted); }

/* Reviews */
.review-list { display: grid; gap: 20px; }
.review-item {
  background: var(--surface); padding: 20px;
  border-radius: var(--radius); border: 1px solid var(--border);
}
.review-header { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.review-avatar { width: 40px; height: 40px; border-radius: 50%; background: #444; flex-shrink: 0; }
.review-name { font-weight: bold; font-size: 15px; }
.review-stars { color: #ffb300; font-size: 12px; margin-top: 2px; }
.review-text { font-size: 14px; color: var(--text-muted); }

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 40px 0 20px;
  text-align: center;
  color: var(--text-muted);
  font-size: 13px;
}
footer p { margin-bottom: 10px; }
.update-time { font-size: 12px; opacity: 0.7; }

/* Responsive */
@media (min-width: 768px) {
  .grid-2 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(3, 1fr); }
  .grid-4 { grid-template-columns: repeat(4, 1fr); }
  .feature-list { grid-template-columns: repeat(2, 1fr); }
  .step-list { grid-template-columns: repeat(2, 1fr); }
  .review-list { grid-template-columns: repeat(2, 1fr); }
  .hero h1 { font-size: 48px; }
}
@media (min-width: 1024px) {
  .feature-list { grid-template-columns: repeat(3, 1fr); }
  .step-list { grid-template-columns: repeat(4, 1fr); }
  .review-list { grid-template-columns: repeat(3, 1fr); }
  .hero h1 { font-size: 56px; }
}