/* ==========================================================================
   xsus机场 品牌官网 - 高效稳定企业级 BGP 全专线 (Enterprise BGP Transit Design System)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=Outfit:wght@400;600;700;800;900&display=swap');

:root {
  /* Color Palette */
  --bg-primary: #F4F6F9;         /* 哑光钛白 Base */
  --bg-secondary: #E9ECEF;
  --bg-dark: #0F172A;            /* 商务深蓝底色 */
  --bg-dark-card: #1E293B;
  --card-glass: rgba(255, 255, 255, 0.85);
  --card-glass-dark: rgba(30, 41, 59, 0.85);

  --text-dark: #0F172A;
  --text-body: #334155;
  --text-muted: #64748B;
  --text-light: #F8FAFC;

  --accent-red: #E11D48;         /* 活力红 / 科技红 */
  --accent-red-hover: #BE123C;
  --accent-blue: #0284C7;        /* 商务科技蓝 */
  --accent-cyan: #0EA5E9;        /* 高清传输蓝弧 */
  --accent-cyan-glow: rgba(14, 165, 233, 0.25);
  --accent-gold: #EAB308;

  --border-light: rgba(226, 232, 240, 0.9);
  --border-glow: rgba(14, 165, 233, 0.3);
  --border-carbon: rgba(255, 255, 255, 0.12);

  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-heading: 'Outfit', 'Inter', sans-serif;

  --shadow-subtle: 0 10px 30px rgba(0, 0, 0, 0.04);
  --shadow-card: 0 20px 40px rgba(15, 23, 42, 0.08);

  --radius-lg: 16px;
  --radius-md: 12px;
  --radius-sm: 8px;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-body);
  line-height: 1.6;
  overflow-x: hidden;
  position: relative;
  background-image: 
    radial-gradient(circle at 10% 20%, rgba(2, 132, 199, 0.03) 0%, transparent 40%),
    radial-gradient(circle at 90% 80%, rgba(225, 29, 72, 0.03) 0%, transparent 40%),
    linear-gradient(to right, rgba(0,0,0,0.015) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(0,0,0,0.015) 1px, transparent 1px);
  background-size: 100% 100%, 100% 100%, 40px 40px, 40px 40px;
}

a {
  color: inherit;
  text-decoration: none;
  transition: all 0.25s ease;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

.container {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header & Nav */
.header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(244, 246, 249, 0.9);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-light);
  transition: all 0.3s ease;
}

.nav-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 80px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 1.5rem;
  color: var(--text-dark);
  letter-spacing: -0.5px;
}

.brand-logo .logo-icon {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, #0F172A, #1E293B);
  border: 1px solid var(--accent-cyan);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent-cyan);
  box-shadow: 0 4px 12px rgba(14, 165, 233, 0.2);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-links a {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text-body);
  position: relative;
  padding: 4px 0;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent-red);
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent-red);
  transition: width 0.3s ease;
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

.header-cta {
  display: flex;
  align-items: center;
  gap: 16px;
}

/* Straightforward Direct Website CTA Button */
.btn-ignition-mini {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: linear-gradient(135deg, var(--accent-red) 0%, #BE123C 100%);
  color: #FFF;
  padding: 12px 26px;
  border-radius: 30px;
  font-weight: 700;
  font-size: 0.95rem;
  font-family: var(--font-heading);
  letter-spacing: 0.3px;
  box-shadow: 0 4px 16px rgba(225, 29, 72, 0.35);
  border: 1px solid rgba(255,255,255,0.3);
  transition: all 0.3s ease;
}

.btn-ignition-mini:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 22px rgba(225, 29, 72, 0.5);
  color: #FFF;
}

.mobile-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text-dark);
  cursor: pointer;
}

/* HERO SECTION */
.hero-section {
  padding: 80px 0 100px;
  position: relative;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}

.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(14, 165, 233, 0.08);
  border: 1px solid rgba(14, 165, 233, 0.2);
  padding: 8px 18px;
  border-radius: 50px;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-blue);
  margin-bottom: 24px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.hero-tag .tag-dot {
  width: 8px;
  height: 8px;
  background: var(--accent-cyan);
  border-radius: 50%;
}

.hero-title {
  font-family: var(--font-heading);
  font-size: 3.2rem;
  font-weight: 900;
  line-height: 1.2;
  color: var(--text-dark);
  margin-bottom: 24px;
  letter-spacing: -1px;
}

.hero-title span.highlight {
  background: linear-gradient(135deg, var(--accent-red) 0%, #0284C7 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-desc {
  font-size: 1.125rem;
  color: var(--text-muted);
  margin-bottom: 36px;
  max-width: 540px;
  line-height: 1.7;
}

/* Central High Performance Engine Box */
.engine-bay-wrapper {
  position: relative;
  background: var(--bg-dark-card);
  border-radius: 24px;
  padding: 28px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  box-shadow: var(--shadow-card);
  color: #FFF;
  overflow: hidden;
}

.engine-glass-cover {
  position: relative;
  background: rgba(255, 255, 255, 0.04);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-carbon);
  border-radius: 18px;
  padding: 24px;
  z-index: 3;
}

.engine-visual-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
  border-bottom: 1px solid rgba(255,255,255,0.1);
  padding-bottom: 12px;
}

.engine-spec-badge {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 1.5px;
  color: var(--accent-cyan);
  text-transform: uppercase;
}

.engine-img-container {
  position: relative;
  border-radius: 14px;
  overflow: hidden;
  margin-bottom: 24px;
  border: 1px solid rgba(14, 165, 233, 0.2);
}

.engine-img-container img {
  width: 100%;
  height: 230px;
  object-fit: cover;
}

/* Dashboard Gauges (RPM & Boost) */
.dashboard-metrics {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 24px;
}

.metric-gauge-card {
  background: rgba(15, 23, 42, 0.8);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 14px;
  padding: 16px;
  text-align: center;
}

.gauge-title {
  font-size: 0.75rem;
  font-weight: 700;
  color: #94A3B8;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 6px;
}

.gauge-value {
  font-family: var(--font-heading);
  font-size: 1.7rem;
  font-weight: 900;
  color: #FFF;
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 4px;
}

.gauge-value .unit {
  font-size: 0.85rem;
  color: var(--accent-cyan);
  font-weight: 600;
}

.gauge-bar-track {
  width: 100%;
  height: 6px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 10px;
  margin-top: 10px;
  overflow: hidden;
}

.gauge-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-red));
  border-radius: 10px;
  width: 92%;
  transition: width 1.5s ease;
}

/* Direct Access Button Box */
.ignition-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 10px 0 5px;
}

.btn-direct-access {
  width: 100%;
  max-width: 320px;
  height: 54px;
  background: linear-gradient(135deg, var(--accent-red) 0%, #BE123C 100%);
  color: #FFF;
  border-radius: 27px;
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 1.05rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  box-shadow: 0 8px 25px rgba(225, 29, 72, 0.4);
  transition: all 0.3s ease;
  border: 1px solid rgba(255,255,255,0.2);
}

.btn-direct-access:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(225, 29, 72, 0.6);
  color: #FFF;
}

.ignition-subtext {
  font-size: 0.8rem;
  color: #94A3B8;
  margin-top: 10px;
  text-align: center;
}

/* Feature Grid Cards */
.section-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 60px;
}

.section-subtitle {
  font-family: var(--font-heading);
  color: var(--accent-red);
  font-weight: 800;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 12px;
  display: block;
}

.section-title {
  font-family: var(--font-heading);
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--text-dark);
  line-height: 1.25;
  letter-spacing: -0.5px;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.feature-card {
  background: #FFF;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 36px 30px;
  transition: all 0.35s ease;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-subtle);
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 0;
  background: var(--accent-red);
  transition: height 0.35s ease;
}

.feature-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-card);
  border-color: rgba(225, 29, 72, 0.3);
}

.feature-card:hover::before {
  height: 100%;
}

.feature-icon-box {
  width: 50px;
  height: 50px;
  background: rgba(14, 165, 233, 0.1);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent-blue);
  margin-bottom: 20px;
}

.feature-card h3 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 12px;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.65;
}

/* Pricing Section */
.pricing-section {
  padding: 100px 0;
  background: linear-gradient(180deg, var(--bg-primary) 0%, #E2E8F0 100%);
  position: relative;
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
  align-items: stretch;
}

.pricing-card {
  background: #FFF;
  border: 1px solid var(--border-light);
  border-radius: 20px;
  padding: 40px 32px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all 0.35s ease;
  position: relative;
}

.pricing-card.popular {
  background: var(--bg-dark-card);
  color: #FFF;
  border: 2px solid var(--accent-red);
  transform: scale(1.04);
  box-shadow: 0 20px 40px rgba(225, 29, 72, 0.2);
}

.popular-badge {
  position: absolute;
  top: -16px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(90deg, var(--accent-red), #0284C7);
  color: #FFF;
  padding: 4px 18px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 1px;
  text-transform: uppercase;
}

.pricing-plan-title {
  font-family: var(--font-heading);
  font-size: 1.35rem;
  font-weight: 800;
  margin-bottom: 8px;
}

.pricing-price {
  font-family: var(--font-heading);
  font-size: 2.8rem;
  font-weight: 900;
  margin-bottom: 24px;
}

.pricing-price span {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-muted);
}

.pricing-card.popular .pricing-price span {
  color: #94A3B8;
}

.pricing-features {
  list-style: none;
  margin-bottom: 36px;
}

.pricing-features li {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.95rem;
  margin-bottom: 14px;
}

.pricing-features li svg {
  color: var(--accent-cyan);
  flex-shrink: 0;
}

.btn-pricing {
  display: block;
  text-align: center;
  padding: 14px 24px;
  border-radius: 30px;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1rem;
  transition: all 0.3s ease;
  background: var(--bg-dark);
  color: #FFF;
}

.pricing-card.popular .btn-pricing {
  background: linear-gradient(135deg, var(--accent-red) 0%, #BE123C 100%);
  color: #FFF;
  box-shadow: 0 6px 20px rgba(225, 29, 72, 0.4);
}

.btn-pricing:hover {
  transform: translateY(-2px);
  opacity: 0.95;
}

/* Target Audience */
.audience-section {
  padding: 100px 0;
}

.audience-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.audience-card {
  background: #FFF;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  text-align: center;
  transition: all 0.3s ease;
}

.audience-card:hover {
  transform: translateY(-5px);
  border-color: var(--accent-cyan);
  box-shadow: var(--shadow-subtle);
}

.audience-avatar {
  width: 56px;
  height: 56px;
  background: rgba(2, 132, 199, 0.08);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 18px;
  color: var(--accent-blue);
}

/* Tutorial Preview Cards */
.tutorial-section {
  padding: 100px 0;
  background: var(--bg-dark-card);
  color: #FFF;
}

.tutorial-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 30px;
}

.tutorial-card {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border-carbon);
  border-radius: 20px;
  padding: 32px;
  transition: all 0.3s ease;
}

.tutorial-card:hover {
  border-color: var(--accent-cyan);
  background: rgba(255, 255, 255, 0.07);
}

.tutorial-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
}

.tutorial-tag {
  background: rgba(14, 165, 233, 0.15);
  color: var(--accent-cyan);
  font-size: 0.75rem;
  font-weight: 800;
  padding: 4px 12px;
  border-radius: 20px;
  text-transform: uppercase;
}

.tutorial-steps {
  margin: 20px 0;
  padding-left: 20px;
  color: #94A3B8;
  font-size: 0.95rem;
}

.tutorial-steps li {
  margin-bottom: 8px;
}

/* Articles Section */
.articles-section {
  padding: 100px 0;
}

.article-cards-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.article-entry-card {
  background: #FFF;
  border-radius: 16px;
  border: 1px solid var(--border-light);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: all 0.35s ease;
}

.article-entry-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-card);
  border-color: var(--accent-cyan);
}

.article-body {
  padding: 24px;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.article-meta {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 10px;
  display: flex;
  gap: 12px;
}

.article-title {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.4;
  color: var(--text-dark);
  margin-bottom: 12px;
}

.article-snippet {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 20px;
  line-height: 1.6;
  flex-grow: 1;
}

.article-link {
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--accent-red);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

/* FAQ Accordion */
.faq-section {
  padding: 100px 0;
  background: #F8FAFC;
}

.faq-list {
  max-width: 860px;
  margin: 0 auto;
}

.faq-item {
  background: #FFF;
  border: 1px solid var(--border-light);
  border-radius: 14px;
  margin-bottom: 16px;
  overflow: hidden;
  transition: all 0.3s ease;
}

.faq-question {
  width: 100%;
  padding: 22px 28px;
  background: none;
  border: none;
  text-align: left;
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-dark);
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
}

.faq-icon {
  font-size: 1.4rem;
  transition: transform 0.3s ease;
  color: var(--accent-red);
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease, padding 0.35s ease;
  padding: 0 28px;
  color: var(--text-muted);
  font-size: 0.98rem;
  line-height: 1.7;
}

.faq-item.active .faq-answer {
  max-height: 500px;
  padding: 0 28px 24px;
}

/* Footer */
.footer {
  background: var(--bg-dark-card);
  color: #94A3B8;
  padding: 80px 0 40px;
  border-top: 1px solid rgba(255,255,255,0.08);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 50px;
  margin-bottom: 60px;
}

.footer-brand p {
  margin-top: 16px;
  font-size: 0.9rem;
  line-height: 1.7;
  max-width: 320px;
}

.footer-column h4 {
  color: #FFF;
  font-family: var(--font-heading);
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 20px;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 12px;
}

.footer-links a {
  color: #94A3B8;
  font-size: 0.9rem;
}

.footer-links a:hover {
  color: var(--accent-cyan);
}

.footer-bottom {
  padding-top: 30px;
  border-top: 1px solid rgba(255,255,255,0.06);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
}

/* Article Layout */
.page-header {
  padding: 60px 0 40px;
  background: var(--bg-dark-card);
  color: #FFF;
  border-bottom: 1px solid var(--border-carbon);
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: #94A3B8;
  margin-bottom: 16px;
}

.breadcrumb a {
  color: var(--accent-cyan);
}

.article-content-wrapper {
  padding: 60px 0;
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 50px;
}

.article-body-main {
  background: #FFF;
  padding: 40px;
  border-radius: 20px;
  border: 1px solid var(--border-light);
}

.article-body-main h1 {
  font-family: var(--font-heading);
  font-size: 2.2rem;
  color: var(--text-dark);
  margin-bottom: 20px;
  line-height: 1.3;
}

.article-body-main h2 {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  color: var(--text-dark);
  margin: 36px 0 18px;
  border-left: 4px solid var(--accent-red);
  padding-left: 14px;
}

.article-body-main h3 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  color: var(--text-dark);
  margin: 24px 0 14px;
}

.article-body-main p {
  font-size: 1.05rem;
  color: #334155;
  line-height: 1.85;
  margin-bottom: 20px;
}

.article-body-main ul, .article-body-main ol {
  margin: 0 0 24px 24px;
  font-size: 1.05rem;
  color: #334155;
  line-height: 1.85;
}

.article-cta-box {
  background: linear-gradient(135deg, #1E293B 0%, #0F172A 100%);
  border-radius: 16px;
  padding: 32px;
  color: #FFF;
  text-align: center;
  margin: 40px 0;
  border: 1px solid var(--accent-cyan);
  box-shadow: var(--shadow-card);
}

.sidebar-widget {
  background: #FFF;
  border: 1px solid var(--border-light);
  border-radius: 16px;
  padding: 24px;
  margin-bottom: 24px;
}

.sidebar-widget h4 {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--bg-primary);
}

/* Mobile Responsiveness */
@media (max-width: 992px) {
  .hero-grid, .features-grid, .pricing-grid, .article-cards-grid, .audience-grid {
    grid-template-columns: 1fr;
  }
  .tutorial-grid {
    grid-template-columns: 1fr;
  }
  .pricing-card.popular {
    transform: none;
  }
  .article-content-wrapper {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
  .hero-title {
    font-size: 2.3rem;
  }
  .nav-links {
    display: none;
  }
  .mobile-toggle {
    display: block;
  }
}