/* ========== Reset & Base ========== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --primary: #1677ff;
  --primary-dark: #0958d9;
  --primary-light: #e6f4ff;
  --bg: #ffffff;
  --bg-secondary: #f5f7fa;
  --text: #1a1a2e;
  --text-secondary: #666;
  --text-muted: #999;
  --border: #e8e8e8;
  --radius: 12px;
  --shadow: 0 2px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
}

html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }

a { color: var(--primary); text-decoration: none; }
a:hover { opacity: 0.8; }

/* ========== Header ========== */
.header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
}
.logo { display: flex; align-items: center; gap: 8px; }
.logo-text { font-size: 20px; font-weight: 700; color: var(--text); }
.nav { display: flex; align-items: center; gap: 20px; flex-shrink: 0; }
.nav a { font-size: 15px; color: var(--text-secondary); transition: color 0.2s; white-space: nowrap; }
.nav a:hover { color: var(--primary); opacity: 1; }
.lang-switch {
  padding: 4px 12px; border: 1px solid var(--border);
  border-radius: 16px; font-size: 13px !important;
}

/* ========== Hero ========== */
.hero {
  padding: 80px 0 60px;
  background: linear-gradient(135deg, #f0f5ff 0%, #e6f4ff 50%, #f5f0ff 100%);
}
.hero .container { display: flex; align-items: center; gap: 60px; }
.hero-content { flex: 1; }
.hero-title { font-size: 48px; font-weight: 800; line-height: 1.2; margin-bottom: 20px; }
.hero-name-en { display: block; color: var(--primary); }
.hero-subtitle { font-size: 22px; color: var(--text-secondary); margin-bottom: 16px; font-weight: 600; }
.hero-desc { font-size: 16px; color: var(--text-secondary); margin-bottom: 32px; line-height: 1.8; }
.hero-buttons { display: flex; gap: 16px; }
.hero-image { flex: 1; display: flex; justify-content: center; }
.hero-mockup {
  width: 320px; height: 520px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  border-radius: 40px; padding: 20px;
  box-shadow: var(--shadow-lg);
  display: flex; align-items: center; justify-content: center;
}
.mockup-screen {
  width: 100%; height: 100%;
  background: rgba(255,255,255,0.15);
  border-radius: 24px; padding: 28px;
  display: flex; flex-direction: column; gap: 24px;
  justify-content: center;
}
.mockup-chord {
  background: rgba(255,255,255,0.25);
  padding: 18px; border-radius: 14px;
  font-size: 20px; font-weight: 700; color: #fff;
  text-align: center; font-family: "SF Mono", Menlo, Consolas, monospace;
  word-break: break-all; overflow: hidden;
}
.mockup-tracks { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; }
.track {
  padding: 10px 16px; border-radius: 20px;
  font-size: 14px; color: #fff; font-weight: 600;
}
.track.vocal { background: rgba(255,107,107,0.75); }
.track.guitar { background: rgba(78,205,196,0.75); }
.track.bass { background: rgba(69,183,209,0.75); }
.track.drum { background: rgba(240,147,251,0.75); }
.track.piano { background: rgba(255,217,61,0.75); }

/* ========== Buttons ========== */
.btn {
  display: inline-block; padding: 12px 28px;
  border-radius: 10px; font-size: 15px; font-weight: 600;
  text-align: center; cursor: pointer; border: none;
  transition: all 0.2s;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); opacity: 1; transform: translateY(-1px); box-shadow: var(--shadow); }
.btn-outline { background: transparent; color: var(--primary); border: 2px solid var(--primary); }
.btn-outline:hover { background: var(--primary-light); opacity: 1; }
.btn-sm { padding: 8px 20px; font-size: 14px; }
.btn-lg { padding: 16px 48px; font-size: 18px; border-radius: 12px; }

/* ========== Sections ========== */
section { padding: 80px 0; }
.section-title {
  font-size: 34px; font-weight: 700; text-align: center;
  margin-bottom: 12px;
}
.section-desc { text-align: center; color: var(--text-secondary); font-size: 16px; margin-bottom: 48px; }

/* ========== Features ========== */
.features { background: var(--bg); }
.features-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.feature-card {
  padding: 32px 24px; border-radius: var(--radius);
  background: var(--bg-secondary); border: 1px solid var(--border);
  transition: transform 0.2s, box-shadow 0.2s;
}
.feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.feature-icon { font-size: 40px; margin-bottom: 16px; }
.feature-card h3 { font-size: 18px; font-weight: 600; margin-bottom: 8px; }
.feature-card p { font-size: 14px; color: var(--text-secondary); line-height: 1.7; }

/* ========== Download ========== */
.download { background: var(--bg-secondary); }
.download-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
}
.download-grid-ios { grid-template-columns: 1fr; max-width: 440px; margin: 0 auto; }
.download-card {
  padding: 32px 20px; border-radius: var(--radius);
  background: var(--bg); border: 1px solid var(--border);
  text-align: center; transition: transform 0.2s, box-shadow 0.2s;
}
.download-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.download-icon { font-size: 40px; margin-bottom: 12px; }
.download-card h3 { font-size: 18px; font-weight: 600; margin-bottom: 8px; }
.download-card p { font-size: 13px; color: var(--text-muted); margin-bottom: 20px; }
.download-card-ios { padding: 40px 24px; }

/* ========== Support ========== */
.support { background: var(--bg); }
.support-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.support-card {
  padding: 32px 24px; border-radius: var(--radius);
  background: var(--bg-secondary); border: 1px solid var(--border);
  text-align: center; transition: transform 0.2s, box-shadow 0.2s;
}
.support-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.support-icon { font-size: 44px; margin-bottom: 14px; }
.support-card h3 { font-size: 18px; font-weight: 600; margin-bottom: 10px; }
.support-card p { font-size: 14px; color: var(--text-secondary); line-height: 1.7; margin-bottom: 20px; }

/* ========== Privacy Policy Page ========== */
.privacy-page { padding: 60px 0 80px; background: var(--bg-secondary); min-height: calc(100vh - 64px - 200px); }
.privacy-content {
  max-width: 860px; margin: 0 auto;
  background: var(--bg); padding: 48px 56px;
  border-radius: 16px; box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
.privacy-content .section-title { margin-bottom: 8px; }
.privacy-date { text-align: center; color: var(--text-muted); font-size: 14px; margin-bottom: 40px; }
.privacy-section { margin-bottom: 32px; }
.privacy-section h2 {
  font-size: 20px; font-weight: 700; margin-bottom: 14px;
  color: var(--text);
}
.privacy-section h3 {
  font-size: 16px; font-weight: 600; margin: 18px 0 10px;
  color: var(--text);
}
.privacy-section p {
  font-size: 15px; color: var(--text-secondary);
  line-height: 1.85; margin-bottom: 12px;
}
.privacy-section strong { color: var(--text); }
.privacy-list { list-style: none; padding: 0; margin: 10px 0; }
.privacy-list li {
  position: relative;
  padding: 8px 0 8px 26px;
  font-size: 15px; color: var(--text-secondary);
  line-height: 1.8;
}
.privacy-list li::before {
  content: "✓";
  position: absolute; left: 0; top: 8px;
  width: 18px; height: 18px; line-height: 18px; text-align: center;
  background: var(--primary-light); color: var(--primary);
  border-radius: 50%; font-size: 12px; font-weight: 700;
}
.privacy-contact {
  background: var(--bg-secondary);
  padding: 24px; border-radius: 12px;
  margin-top: 10px;
}
.privacy-contact p { margin-bottom: 6px; }

/* ========== Footer ========== */
.footer { background: var(--text); color: #fff; padding: 40px 0; }
.footer-inner { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 16px; }
.footer-brand { display: flex; align-items: center; gap: 8px; font-size: 18px; font-weight: 600; }
.footer-links { display: flex; gap: 24px; }
.footer-links a { color: rgba(255,255,255,0.7); font-size: 14px; }
.footer-links a:hover { color: #fff; opacity: 1; }
.footer-copy p { font-size: 13px; color: rgba(255,255,255,0.5); }
.footer-icp { margin-top: 6px; }
.footer-icp a { color: rgba(255,255,255,0.4); font-size: 12px; }
.footer-icp a:hover { color: rgba(255,255,255,0.7); opacity: 1; }

/* ========== Responsive ========== */
@media (max-width: 960px) {
  .hero .container { flex-direction: column-reverse; gap: 32px; text-align: center; }
  .hero-buttons { justify-content: center; }
  .features-grid, .support-grid { grid-template-columns: repeat(2, 1fr); }
  .privacy-content { padding: 32px 24px; }
}
@media (max-width: 768px) {
  .hero-title { font-size: 36px; }
  .hero-subtitle { font-size: 18px; }
  .hero-mockup { width: 260px; height: 400px; }
  .features-grid, .support-grid { grid-template-columns: 1fr; }
  .download-grid { grid-template-columns: repeat(2, 1fr); }
  .nav { gap: 14px; }
  .nav a { font-size: 13px; }
}
@media (max-width: 560px) {
  .container { padding: 0 16px; }
  section { padding: 60px 0; }
  .header-inner { height: 56px; }
  .nav { gap: 10px; }
  .nav a { font-size: 12px; }
  .lang-switch { padding: 3px 8px; font-size: 11px !important; }
  .hero { padding: 48px 0 40px; }
  .hero-title { font-size: 30px; }
  .hero-mockup { width: 240px; height: 360px; }
  .download-grid { grid-template-columns: 1fr; }
  .hero-buttons { flex-direction: column; gap: 12px; align-items: stretch; }
  .privacy-content { padding: 24px 18px; border-radius: 12px; }
  .privacy-content .section-title { font-size: 26px; }
  .privacy-section h2 { font-size: 18px; }
  .footer-inner { flex-direction: column; text-align: center; gap: 20px; }
}