/* ================================================================
   V-Art Apple-Style Design System
   Reference: apple.com.cn — high-end, minimal, tech
   ================================================================ */
:root {
  --bg-dark: #000000;
  --bg-light: #f5f5f7;
  --bg-white: #ffffff;
  --text-dark: #1d1d1f;
  --text-light: #f5f5f7;
  --text-muted: #86868b;
  --accent: #0071e3;
  --accent-hover: #0077ed;
  --ff: -apple-system, BlinkMacSystemFont, "SF Pro SC", "SF Pro Text", "PingFang SC", "Helvetica Neue", sans-serif;
  --radius: 18px;
  --radius-sm: 12px;
  --max-w: 980px;
  --nav-h: 48px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--ff);
  background: var(--bg-white);
  color: var(--text-dark);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
img { max-width: 100%; display: block; }
a { color: var(--accent); text-decoration: none; transition: color 0.3s; }
a:hover { color: var(--accent-hover); }
button { font-family: inherit; cursor: pointer; }
ul { list-style: none; }

/* ============ Typography ============ */
.display-title { font-size: 64px; font-weight: 700; letter-spacing: -0.015em; line-height: 1.05; }
.section-title { font-size: 48px; font-weight: 700; letter-spacing: -0.015em; line-height: 1.1; }
.section-sub { font-size: 21px; color: var(--text-muted); font-weight: 400; line-height: 1.4; }
.eyebrow { font-size: 14px; font-weight: 600; color: var(--accent); text-transform: uppercase; letter-spacing: 0.05em; }
@media (max-width: 768px) {
  .display-title { font-size: 40px; }
  .section-title { font-size: 32px; }
  .section-sub { font-size: 17px; }
}

/* ============ Nav ============ */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: rgba(0,0,0,0.8);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  height: var(--nav-h);
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 32px;
}
.nav-logo { color: #fff; font-size: 17px; font-weight: 600; letter-spacing: -0.02em; }
.nav-links { display: flex; gap: 32px; }
.nav-links a { color: rgba(255,255,255,0.8); font-size: 12px; }
.nav-links a:hover { color: #fff; }
.nav-right { display: flex; gap: 16px; align-items: center; }
.nav-right select {
  background: transparent; color: rgba(255,255,255,0.8); border: none;
  font-size: 12px; font-family: var(--ff); cursor: pointer; outline: none;
}
.nav-right select option { color: #000; }
.nav-right a { color: rgba(255,255,255,0.8); font-size: 12px; }
.nav-right a:hover { color: #fff; }


/* ============ Hero ============ */
.hero {
  background: #000;
  color: var(--text-light);
  text-align: center;
  padding: 140px 24px 100px;
  min-height: 100vh;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
}
.hero-eyebrow { color: var(--text-muted); font-size: 17px; font-weight: 600; margin-bottom: 16px; }
.hero-title { font-size: 64px; font-weight: 700; letter-spacing: -0.015em; line-height: 1.05; margin-bottom: 16px; }
.hero-title em { font-style: normal; background: linear-gradient(90deg, #ff6a00, #ee0979, #a855f7, #38bdf8); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.hero-sub { font-size: 24px; color: var(--text-muted); font-weight: 400; margin-bottom: 40px; }
.hero-cta { display: flex; gap: 20px; margin-top: 80px; }
@media (max-width: 768px) {
  .hero { padding: 120px 24px 80px; }
  .hero-title { font-size: 40px; }
  .hero-sub { font-size: 18px; }
}

/* ============ Sections ============ */
.section { padding: 100px 24px; text-align: center; }
.section-light { background: var(--bg-light); }
.section-dark { background: #000; color: var(--text-light); }
.section-dark .section-sub { color: #a0a0b0; }
.section-narrow { max-width: var(--max-w); margin: 0 auto; }
.container { max-width: 1180px; margin: 0 auto; }

/* ============ Buttons ============ */
.btn {
  display: inline-block; padding: 12px 32px; border-radius: 980px;
  font-size: 17px; font-family: var(--ff); text-decoration: none; transition: all 0.3s;
  border: none; cursor: pointer;
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-hover); color: #fff; }
.btn-link { background: transparent; color: var(--accent); padding: 12px 8px; }
.btn-link:hover { text-decoration: underline; color: var(--accent-hover); }
.btn-dark { background: #1d1d1f; color: #fff; }
.btn-dark:hover { background: #333; color: #fff; }
.btn-outline { background: transparent; color: var(--text-dark); border: 1px solid #d2d2d7; }
.btn-outline:hover { border-color: var(--text-dark); }

/* ============ Product Card ============ */
.product-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
@media (max-width: 900px) { .product-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 500px) { .product-grid { grid-template-columns: 1fr; } }
.product-card {
  background: #fff; border-radius: 16px; overflow: hidden; text-decoration: none; color: inherit;
  box-shadow: 0 2px 12px rgba(0,0,0,0.06); transition: transform 0.3s, box-shadow 0.3s;
}
.product-card:hover { transform: translateY(-4px); box-shadow: 0 12px 32px rgba(0,0,0,0.12); }
.product-img { aspect-ratio: 1; display: flex; align-items: center; justify-content: center; font-size: 96px; }
.product-info { padding: 16px; text-align: left; }
.product-name { font-size: 16px; font-weight: 600; }
.product-series { font-size: 12px; color: var(--text-muted); margin: 4px 0; }
.product-price { font-size: 15px; font-weight: 600; }

.product-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; max-width: 1180px; margin: 0 auto; }
@media (max-width: 900px) { .product-row { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 500px) { .product-row { grid-template-columns: 1fr; } }

/* ============ Series Card ============ */
.series-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
@media (max-width: 768px) { .series-grid { grid-template-columns: 1fr; } }
.series-card { border-radius: var(--radius); overflow: hidden; text-decoration: none; color: inherit; transition: transform 0.4s; }
.series-card:hover { transform: scale(1.02); }
.series-image { aspect-ratio: 3/4; display: flex; align-items: center; justify-content: center; font-size: 60px; }
.series-body { background: #fff; padding: 24px; text-align: left; }
.series-name { font-size: 20px; font-weight: 600; margin-bottom: 4px; }
.series-desc { font-size: 14px; color: var(--text-muted); }

/* ============ Feature Card ============ */
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
@media (max-width: 768px) { .feature-grid { grid-template-columns: 1fr; } }
.feature-card { background: #fff; border-radius: var(--radius); padding: 40px 32px; box-shadow: 0 4px 24px rgba(0,0,0,0.06); text-align: left; }
.feature-icon { font-size: 40px; margin-bottom: 16px; }
.feature-title { font-size: 20px; font-weight: 600; margin-bottom: 8px; }
.feature-desc { font-size: 15px; color: var(--text-muted); line-height: 1.6; }

/* ============ Demo Phone (OFF/ON) ============ */
.demo-phone {
  width: 280px; height: 580px; border-radius: 40px;
  background: #111; border: 2px solid #333; position: relative;
  margin: 40px auto; overflow: hidden; box-shadow: 0 40px 80px rgba(0,0,0,0.5);
}
.demo-screen { position: absolute; inset: 0; background: radial-gradient(circle at 30% 20%, #1a1a2e, #000); }
.demo-art {
  position: absolute; inset: 0; display: flex; align-items: center; justify-content: center;
  background: radial-gradient(circle at 50% 50%, #1e1b4b 0%, #3b1d8e 40%, #7c3aed 70%, #ec4899 100%);
  opacity: 1; transition: opacity 1s ease;
}
.demo-art .art-inner { font-size: 90px; color: rgba(255,255,255,0.9); text-shadow: 0 0 40px rgba(168,85,247,0.8); }
.demo-art.hidden { opacity: 0; }
.demo-time { position: absolute; top: 60px; left: 0; right: 0; text-align: center; font-size: 48px; font-weight: 300; color: rgba(255,255,255,0.9); }
.demo-toggle {
  position: absolute; bottom: -70px; left: 50%; transform: translateX(-50%);
  background: var(--accent); color: #fff; border: none; padding: 12px 32px;
  border-radius: 980px; font-size: 16px; cursor: pointer; transition: background 0.3s;
}
.demo-toggle:hover { background: var(--accent-hover); }

/* ============ Footer ============ */
.footer { background: var(--bg-light); padding: 60px 24px 40px; }
.footer-inner { max-width: var(--max-w); margin: 0 auto; }
.footer-links { display: grid; grid-template-columns: repeat(4, 1fr); gap: 32px; margin-bottom: 40px; }
@media (max-width: 768px) { .footer-links { grid-template-columns: repeat(2, 1fr); } }
.footer-col h4 { font-size: 12px; font-weight: 600; color: var(--text-dark); margin-bottom: 12px; }
.footer-col a { display: block; font-size: 12px; color: var(--text-muted); padding: 4px 0; }
.footer-col a:hover { text-decoration: underline; color: var(--text-dark); }
.footer-bottom { border-top: 1px solid #d2d2d7; padding-top: 20px; font-size: 12px; color: var(--text-muted); text-align: center; }

/* ============ Utilities ============ */
.text-center { text-align: center; }
.mt-20 { margin-top: 20px; }
.mt-40 { margin-top: 40px; }
.mt-60 { margin-top: 60px; }
.hide-mobile { display: block; }
@media (max-width: 768px) { .hide-mobile { display: none; } }