:root {
  --bg-main: #F8FAFC;
  --bg-card: #FFFFFF;
  --bg-dark: #0F172A;
  --bg-dark-2: #1E293B;
  --text-main: #0F172A;
  --text-muted: #475569;
  --accent-orange: #FF5500;
  --accent-crimson: #E11D48;
  --accent-gold: #F59E0B;
  --border-light: #E2E8F0;
  --shadow-lg: 0 20px 45px -12px rgba(15, 23, 42, 0.12);
  --shadow-orange: 0 12px 30px -6px rgba(255, 85, 0, 0.32);
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-family: "PingFang SC", "Microsoft YaHei", -apple-system, BlinkMacSystemFont, sans-serif; background: var(--bg-main); color: var(--text-main); line-height: 1.68; }
body { overflow-x: hidden; background-image: radial-gradient(circle at 88% 8%, rgba(255,85,0,0.08) 0%, transparent 42%), radial-gradient(circle at 12% 35%, rgba(225,29,72,0.06) 0%, transparent 38%); }
a, a:visited { color: #D93800; text-decoration: underline; text-underline-offset: 3px; font-weight: 600; transition: color 0.2s ease, opacity 0.2s ease; }
a:hover { color: var(--accent-crimson); }
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }

/* Header & Navigation */
.site-header { position: sticky; top: 0; z-index: 100; background: rgba(248, 250, 252, 0.94); backdrop-filter: blur(12px); border-bottom: 2px solid var(--border-light); }
.nav-wrap { display: flex; align-items: center; justify-content: space-between; padding: 14px 0; gap: 16px; }
.brand-link, .brand-link:visited { display: inline-flex; align-items: center; gap: 10px; font-size: 1.38rem; font-weight: 900; color: var(--text-main); text-decoration: none; letter-spacing: -0.02em; }
.brand-badge { font-size: 0.72rem; background: linear-gradient(90deg, var(--accent-orange), var(--accent-crimson)); color: #fff; padding: 2px 8px; border-radius: 99px; font-weight: 700; text-transform: uppercase; }
.main-nav { display: flex; align-items: center; flex-wrap: wrap; gap: 8px 18px; }
.main-nav a, .main-nav a:visited { color: var(--text-main); text-decoration: none; font-size: 0.96rem; font-weight: 700; padding: 6px 10px; border-radius: 8px; transition: all 0.2s; }
.main-nav a:hover { color: var(--accent-orange); background: rgba(255, 85, 0, 0.08); }
.nav-cta, .nav-cta:visited { background: linear-gradient(135deg, var(--accent-orange), var(--accent-crimson)); color: #FFFFFF !important; text-decoration: none !important; padding: 9px 18px; border-radius: 999px; font-size: 0.92rem; font-weight: 800; box-shadow: var(--shadow-orange); display: inline-flex; align-items: center; gap: 6px; white-space: nowrap; }
.nav-cta:hover { transform: translateY(-1px); opacity: 0.95; }

/* Buttons */
.btn-row { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; margin-top: 26px; }
.btn-primary, .btn-primary:visited { display: inline-flex; align-items: center; gap: 9px; background: linear-gradient(135deg, var(--accent-orange) 0%, var(--accent-crimson) 100%); color: #FFFFFF !important; text-decoration: none !important; padding: 15px 30px; border-radius: 12px; font-size: 1.05rem; font-weight: 800; box-shadow: var(--shadow-orange); transition: transform 0.2s, box-shadow 0.2s; border: none; cursor: pointer; }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 16px 36px -6px rgba(225, 29, 72, 0.45); }
.btn-secondary, .btn-secondary:visited { display: inline-flex; align-items: center; gap: 8px; background: var(--bg-dark); color: #FFFFFF !important; text-decoration: none !important; padding: 15px 26px; border-radius: 12px; font-size: 1.02rem; font-weight: 800; border: 2px solid var(--accent-gold); transition: transform 0.2s, background 0.2s; }
.btn-secondary:hover { background: var(--bg-dark-2); transform: translateY(-2px); }

/* Hero Section */
.hero { padding: 58px 0 68px; position: relative; overflow: hidden; }
.hero-grid { display: grid; grid-template-columns: 1.08fr 0.92fr; gap: 40px; align-items: center; }
.sonic-tag { display: inline-flex; align-items: center; gap: 8px; background: rgba(255, 85, 0, 0.12); color: #C23B00; border: 1px solid rgba(255, 85, 0, 0.32); padding: 6px 14px; border-radius: 999px; font-size: 0.86rem; font-weight: 800; margin-bottom: 18px; }
.hero h1 { font-size: clamp(2.1rem, 3.8vw, 3.25rem); line-height: 1.18; font-weight: 900; color: var(--bg-dark); letter-spacing: -0.025em; margin-bottom: 18px; }
.hero h1 .hl { background: linear-gradient(90deg, var(--accent-orange), var(--accent-crimson)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.hero-lead { font-size: 1.1rem; color: var(--text-muted); margin-bottom: 20px; max-width: 580px; }
.hero-metrics { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin-top: 30px; padding-top: 24px; border-top: 1px solid var(--border-light); }
.metric-box { background: var(--bg-card); padding: 14px 16px; border-radius: 12px; border-left: 4px solid var(--accent-orange); box-shadow: 0 4px 14px rgba(15,23,42,0.05); }
.metric-val { font-size: 1.45rem; font-weight: 900; color: var(--bg-dark); }
.metric-lbl { font-size: 0.84rem; color: var(--text-muted); font-weight: 600; }

/* Animated SVG Stage */
.sonic-stage { background: linear-gradient(150deg, #0F172A 0%, #1E293B 65%, #311022 100%); border-radius: 22px; padding: 22px; box-shadow: var(--shadow-lg); border: 2px solid rgba(255, 85, 0, 0.35); position: relative; overflow: hidden; }
.sonic-stage-header { display: flex; justify-content: space-between; align-items: center; color: #F8FAFC; font-size: 0.84rem; font-weight: 700; margin-bottom: 10px; padding: 0 6px; }
.mach-pill { background: linear-gradient(90deg, #FF5500, #F59E0B); color: #0F172A; padding: 3px 11px; border-radius: 99px; font-weight: 900; font-size: 0.78rem; }
@keyframes pulseBoom { 0%, 100% { transform: scale(0.95); opacity: 0.75; } 50% { transform: scale(1.06); opacity: 1; } }
@keyframes wingFloat { 0%, 100% { transform: translateY(0px) translateX(0px); } 50% { transform: translateY(-7px) translateX(5px); } }
.wing-glider { animation: wingFloat 3.4s ease-in-out infinite; transform-origin: center; }
.boom-ring { animation: pulseBoom 2.4s ease-in-out infinite; transform-origin: center; }

/* Sections */
.section { padding: 68px 0; }
.section-alt { background: #F1F5F9; }
.section-dark { background: var(--bg-dark); color: #F8FAFC; }
.sec-head { text-align: center; max-width: 760px; margin: 0 auto 44px; }
.sec-tag { display: inline-block; font-size: 0.82rem; font-weight: 800; text-transform: uppercase; letter-spacing: 0.08em; color: var(--accent-orange); background: rgba(255,85,0,0.1); padding: 4px 12px; border-radius: 99px; margin-bottom: 10px; }
.sec-head h2 { font-size: clamp(1.7rem, 2.8vw, 2.35rem); font-weight: 900; margin-bottom: 12px; letter-spacing: -0.02em; }
.sec-head p { color: var(--text-muted); font-size: 1.02rem; }
.section-dark .sec-head p { color: #94A3B8; }

/* Feature Grid */
.feat-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.feat-card { background: var(--bg-card); border-radius: 16px; padding: 28px 24px; border: 1px solid var(--border-light); box-shadow: 0 8px 24px rgba(15,23,42,0.04); transition: transform 0.2s, border-color 0.2s; position: relative; overflow: hidden; }
.feat-card::before { content: ""; position: absolute; top: 0; left: 0; width: 100%; height: 4px; background: linear-gradient(90deg, var(--accent-orange), var(--accent-crimson), var(--accent-gold)); }
.feat-card:hover { transform: translateY(-4px); border-color: var(--accent-orange); }
.feat-icon { width: 48px; height: 48px; border-radius: 12px; background: rgba(255,85,0,0.12); color: var(--accent-orange); display: flex; align-items: center; justify-content: center; margin-bottom: 16px; }
.feat-card h3 { font-size: 1.2rem; font-weight: 800; margin-bottom: 10px; }
.feat-card p { color: var(--text-muted); font-size: 0.95rem; }

/* Interactive Sonic Tunnel Simulator */
.sim-panel { background: var(--bg-card); border-radius: 20px; padding: 32px; border: 2px solid var(--border-light); box-shadow: var(--shadow-lg); }
.sim-tabs { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 24px; }
.sim-tab { padding: 11px 20px; border-radius: 10px; border: 2px solid var(--border-light); background: #F8FAFC; font-weight: 800; font-size: 0.95rem; cursor: pointer; color: var(--text-main); transition: all 0.2s; }
.sim-tab.active { background: linear-gradient(135deg, var(--accent-orange), var(--accent-crimson)); color: #fff; border-color: transparent; box-shadow: var(--shadow-orange); }
.sim-body { display: grid; grid-template-columns: 1.2fr 0.8fr; gap: 24px; align-items: center; background: #0F172A; color: #F8FAFC; padding: 26px; border-radius: 16px; }
.sim-stats { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; }
.sim-stat-box { background: rgba(255,255,255,0.06); padding: 14px; border-radius: 10px; border-left: 3px solid var(--accent-gold); }
.sim-stat-box span { display: block; font-size: 0.8rem; color: #94A3B8; }
.sim-stat-box strong { font-size: 1.25rem; color: #F8FAFC; }

/* Comparison Table */
.table-wrap { overflow-x: auto; background: var(--bg-card); border-radius: 16px; border: 1px solid var(--border-light); box-shadow: var(--shadow-lg); }
.comp-table { width: 100%; border-collapse: collapse; min-width: 640px; }
.comp-table th, .comp-table td { padding: 16px 20px; text-align: left; border-bottom: 1px solid var(--border-light); font-size: 0.95rem; }
.comp-table th { background: var(--bg-dark); color: #FFFFFF; font-weight: 800; }
.comp-table th.hl-col { background: linear-gradient(135deg, var(--accent-orange), var(--accent-crimson)); }
.comp-table td.hl-col { background: rgba(255, 85, 0, 0.05); font-weight: 700; color: var(--bg-dark); }

/* Pricing Grid */
.price-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; align-items: stretch; }
.price-card { background: var(--bg-card); color: var(--text-main); border-radius: 18px; padding: 32px 26px; border: 2px solid var(--border-light); display: flex; flex-direction: column; justify-content: space-between; position: relative; }
.price-card.pop { border-color: var(--accent-orange); box-shadow: var(--shadow-orange); transform: translateY(-6px); }
.pop-badge { position: absolute; top: -13px; right: 22px; background: linear-gradient(90deg, var(--accent-orange), var(--accent-crimson)); color: #fff; font-size: 0.78rem; font-weight: 800; padding: 4px 14px; border-radius: 99px; }
.price-num { font-size: 2.3rem; font-weight: 900; color: var(--bg-dark); margin: 14px 0; }
.price-num small { font-size: 0.92rem; color: var(--text-muted); font-weight: 600; }
.price-list { list-style: none; margin: 18px 0 26px; display: flex; flex-direction: column; gap: 11px; }
.price-list li { display: flex; align-items: center; gap: 8px; font-size: 0.94rem; }
.price-list li svg { color: var(--accent-orange); flex-shrink: 0; }

/* Articles Preview & Hub */
.art-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.art-card { background: var(--bg-card); border-radius: 15px; padding: 24px; border: 1px solid var(--border-light); display: flex; flex-direction: column; justify-content: space-between; transition: transform 0.2s, box-shadow 0.2s; }
.art-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--accent-orange); }
.art-meta { font-size: 0.8rem; font-weight: 700; color: var(--accent-orange); margin-bottom: 8px; display: flex; justify-content: space-between; }
.art-card h3 { font-size: 1.12rem; font-weight: 800; margin-bottom: 10px; line-height: 1.42; }
.art-card h3 a, .art-card h3 a:visited { color: var(--bg-dark); text-decoration: none; }
.art-card h3 a:hover { color: var(--accent-orange); }
.art-card p { font-size: 0.91rem; color: var(--text-muted); margin-bottom: 16px; }

/* FAQ Accordion */
.faq-list { max-width: 860px; margin: 0 auto; display: flex; flex-direction: column; gap: 14px; }
.faq-item { background: var(--bg-card); border: 1px solid var(--border-light); border-radius: 14px; padding: 18px 22px; }
.faq-item summary { font-weight: 800; font-size: 1.04rem; cursor: pointer; list-style: none; display: flex; justify-content: space-between; align-items: center; }
.faq-item summary::after { content: "+"; font-size: 1.35rem; color: var(--accent-orange); font-weight: 900; }
.faq-item[open] summary::after { content: "−"; }
.faq-item p { margin-top: 12px; color: var(--text-muted); font-size: 0.95rem; border-top: 1px solid var(--border-light); padding-top: 12px; }

/* Article Detail Layout */
.article-wrap { max-width: 860px; margin: 44px auto 70px; background: var(--bg-card); border-radius: 20px; padding: 44px; border: 1px solid var(--border-light); box-shadow: var(--shadow-lg); }
.breadcrumb { font-size: 0.88rem; color: var(--text-muted); margin-bottom: 18px; }
.article-wrap h1 { font-size: clamp(1.65rem, 2.8vw, 2.25rem); font-weight: 900; line-height: 1.3; margin-bottom: 14px; color: var(--bg-dark); }
.art-byline { display: flex; flex-wrap: wrap; gap: 16px; font-size: 0.86rem; color: var(--text-muted); padding-bottom: 20px; margin-bottom: 26px; border-bottom: 2px solid var(--border-light); }
.art-content h2 { font-size: 1.38rem; font-weight: 800; color: var(--bg-dark); margin: 28px 0 12px; padding-left: 12px; border-left: 4px solid var(--accent-orange); }
.art-content h3 { font-size: 1.14rem; font-weight: 800; color: var(--bg-dark-2); margin: 20px 0 10px; }
.art-content p { margin-bottom: 16px; font-size: 1.01rem; color: #1E293B; line-height: 1.8; }
.cta-banner { background: linear-gradient(135deg, #0F172A 0%, #271123 100%); color: #fff; border-radius: 16px; padding: 28px; margin: 34px 0; border: 1px solid var(--accent-orange); display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: 18px; }

/* Footer */
.site-footer { background: var(--bg-dark); color: #CBD5E1; padding: 42px 0; border-top: 4px solid var(--accent-orange); }
.footer-inner { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: 20px; }
.footer-links { display: flex; flex-wrap: wrap; gap: 22px; }
.footer-links a, .footer-links a:visited { color: #F59E0B; text-decoration: none; font-weight: 700; font-size: 0.95rem; }
.footer-links a:hover { color: #FF5500; text-decoration: underline; }

/* Responsive - Rule 7: Mobile navigation MUST remain visible */
@media (max-width: 920px) {
  .hero-grid, .feat-grid, .price-grid, .art-grid, .sim-body { grid-template-columns: 1fr; }
  .price-card.pop { transform: none; }
}
@media (max-width: 768px) {
  .nav-wrap { flex-direction: column; align-items: flex-start; gap: 10px; }
  .main-nav { width: 100%; display: flex !important; flex-wrap: wrap; gap: 6px 10px; padding-top: 6px; border-top: 1px solid var(--border-light); }
  .main-nav a { font-size: 0.88rem; padding: 5px 8px; }
  .hero { padding: 34px 0 46px; }
  .hero-metrics { grid-template-columns: 1fr; }
  .article-wrap { padding: 24px 18px; margin: 22px auto 46px; }
}