/* ============================================================
   A2A Hub Common Styles V2.0 — Bilingual, Nav, Shared Rules
   ============================================================ */

/* === Bilingual Display Control === */
[lang-en] { display: none; }
html[lang="en"] [lang-zh] { display: none; }
html[lang="en"] [lang-en] { display: inline; }

html[lang="en"] .a2a-lang-only-zh { display: none !important; }
html:not([lang="en"]) .a2a-lang-only-en { display: none !important; }

/* === Language Toggle Button === */
.a2a-lang-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--border-light);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 700;
  padding: 6px 14px;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  text-decoration: none;
  min-width: 44px;
  letter-spacing: 0.5px;
}
.a2a-lang-toggle:hover {
  background: rgba(230,194,110,0.1);
  border-color: var(--gold);
  color: var(--gold);
}

/* Language toggle separator in nav */
.a2a-nav-links .a2a-lang-toggle {
  border-left: 1px solid rgba(255,255,255,0.15);
  padding-left: 16px;
  margin-left: 0;
}

/* === Scroll Spy Active Nav === */
.a2a-nav-links a.a2a-nav-active {
  color: var(--gold) !important;
  background: rgba(230,194,110,0.08);
}

/* === Mobile Hamburger === */
@media (max-width: 768px) {
  .a2a-nav-right-group {
    display: flex;
    align-items: center;
    gap: 10px;
  }
}

/* === Comparison Table (A2A vs MCP) === */
.a2a-comparison-table {
  width: 100%;
  table-layout: fixed;
  border-collapse: collapse;
  margin-top: 40px;
  font-size: 14px;
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--border-light);
}
.a2a-comparison-table th {
  background: rgba(230,194,110,0.08);
  color: var(--gold);
  font-weight: 700;
  padding: 14px 20px;
  text-align: left;
  font-size: 15px;
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.a2a-comparison-table td {
  padding: 12px 20px;
  border-bottom: 1px solid rgba(255,255,255,0.04);
  color: var(--text-primary);
  vertical-align: top;
  line-height: 1.5;
}
.a2a-comparison-table tr:last-child td {
  border-bottom: none;
}
.a2a-comparison-table tr:hover td {
  background: var(--section-bg);
}
.a2a-comparison-table td:first-child {
  font-weight: 700;
  color: var(--text-secondary);
  white-space: nowrap;
  width: 120px;
}

/* === Tech Spec Grid (M4) === */
.a2a-techspec-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 40px;
}
.a2a-techspec-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 12px;
  padding: 28px 24px;
  transition: all 0.3s ease;
  position: relative;
}
.a2a-techspec-card:hover {
  border-color: rgba(230,194,110,0.3);
  background: rgba(17,28,48,0.9);
  transform: translateY(-3px);
}
.a2a-techspec-num {
  font-family: "Outfit", sans-serif;
  font-size: 11px;
  font-weight: 700;
  color: var(--gold);
  letter-spacing: 1.5px;
  margin-bottom: 10px;
  opacity: 0.7;
}
.a2a-techspec-card h4 {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
}
.a2a-techspec-card p {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.6;
}
.a2a-techspec-std {
  display: inline-block;
  margin-top: 10px;
  font-size: 11px;
  font-family: "JetBrains Mono", monospace;
  color: var(--gold-dark);
  background: rgba(212,160,80,0.08);
  padding: 4px 10px;
  border-radius: 6px;
}

/* === Roadmap Timeline (E1) === */
.a2a-roadmap-timeline {
  position: relative;
  margin-top: 48px;
  padding-left: 40px;
}
.a2a-roadmap-timeline::before {
  content: "";
  position: absolute;
  left: 18px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(180deg, var(--gold), rgba(230,194,110,0.1));
}
.a2a-roadmap-node {
  position: relative;
  margin-bottom: 32px; padding-bottom: 32px;
  padding-left: 32px;
}
.a2a-roadmap-node::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 6px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--gold);
  border: 3px solid var(--bg);
  box-shadow: 0 0 12px rgba(230,194,110,0.4);
}
.a2a-roadmap-date {
  font-size: 13px;
  font-family: "JetBrains Mono", monospace;
  color: var(--gold);
  font-weight: 700;
  margin-bottom: 6px;
}
.a2a-roadmap-node h4 {
  font-size: 17px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}
.a2a-roadmap-node p {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* === Trust Anchors (E2) === */
.a2a-trust-anchors {
  display: flex;
  gap: 20px;
  justify-content: center;
  flex-wrap: wrap;
  padding: 32px 0;
  border-top: 1px solid var(--border-light);
  border-bottom: 1px solid var(--border-light);
  margin: 0 auto 40px;
  max-width: 1280px;
}
.a2a-trust-anchor-card {
  text-align: center;
  padding: 20px 28px;
  border-radius: 12px;
  background: rgba(13,21,37,0.6);
  border: 1px solid rgba(255,255,255,0.05);
  min-width: 160px;
  transition: all 0.3s ease;
}
.a2a-trust-anchor-card:hover {
  border-color: rgba(230,194,110,0.2);
  background: rgba(17,28,48,0.8);
}
.a2a-trust-anchor-icon {
  font-size: 28px;
  margin-bottom: 8px;
}
.a2a-trust-anchor-card h4 {
  font-size: 13px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}
.a2a-trust-anchor-card .a2a-trust-anchor-badge {
  font-size: 10px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 10px;
  display: inline-block;
}
.a2a-trust-anchor-badge.certified {
  background: rgba(124,197,118,0.12);
  color: #7CC576;
}
.a2a-trust-anchor-badge.target {
  background: rgba(212,160,80,0.12);
  color: var(--gold-dark);
}

/* === Code Highlight (E4) === */
.a2a-code-block {
  background: rgba(0,0,0,0.35);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 8px;
  padding: 16px 20px;
  font-family: "JetBrains Mono", "Consolas", monospace;
  font-size: 13px;
  line-height: 1.65;
  overflow-x: auto;
  color: var(--text-primary);
  white-space: pre;
}
.a2a-code-block .kw  { color: var(--gold-dark); font-weight: 600; }  /* keyword */
.a2a-code-block .str { color: #7CC576; }                     /* string */
.a2a-code-block .fn  { color: #4A90E2; }                     /* function */
.a2a-code-block .cm  { color: var(--text-tertiary); font-style: italic; } /* comment */
.a2a-code-block .num { color: #9B59B6; }                     /* number */
.a2a-code-block .prop { color: var(--gold); }                    /* property */

/* === ROI Badge (E3) === */
.a2a-roi-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 12px;
  padding: 5px 12px;
  border-radius: 20px;
  background: rgba(124,197,118,0.08);
  color: #7CC576;
  font-size: 12px;
  font-weight: 700;
}
.a2a-roi-badge::before {
  content: "↑";
  font-size: 14px;
}

/* === Stats Data Note (H4) === */
.a2a-data-note {
  font-size: 10px;
  color: var(--text-tertiary);
  margin-top: 4px;
  font-style: italic;
}

/* === Footer Subscribe (Phase 4) === */
.a2a-footer-subscribe {
  display: flex;
  gap: 10px;
  max-width: 400px;
  margin: 20px auto 0;
}
.a2a-footer-subscribe input {
  flex: 1;
  background: rgba(255,255,255,0.05);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 24px;
  padding: 12px 20px;
  color: var(--text-primary);
  font-size: 14px;
  outline: none;
  transition: border-color 0.3s;
}
.a2a-footer-subscribe input:focus {
  border-color: var(--gold);
}
.a2a-footer-subscribe .a2a-btn-subscribe {
  background: var(--gold-gradient);
  color: var(--bg);
  border: none;
  border-radius: 24px;
  padding: 12px 24px;
  font-weight: 700;
  font-size: 14px;
  cursor: pointer;
  transition: all 0.3s;
}
.a2a-footer-subscribe .a2a-btn-subscribe:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(230,194,110,0.3);
}

/* === Footer 5-column layout === */
.a2a-footer-links-5col {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 24px;
  padding: 48px 32px;
  max-width: 1280px;
  margin: 0 auto 40px;
}

@media (max-width: 1024px) {
  .a2a-techspec-grid { grid-template-columns: repeat(2, 1fr); }
  .a2a-footer-links-5col { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 768px) {
  .a2a-techspec-grid { grid-template-columns: 1fr; }
  .a2a-footer-links-5col { grid-template-columns: repeat(2, 1fr); }
  .a2a-roadmap-timeline { padding-left: 30px; }
  .a2a-roadmap-node { padding-left: 20px; }
  .a2a-comparison-table { font-size: 12px; }
  .a2a-comparison-table th, .a2a-comparison-table td { padding: 10px 12px; }
}
@media (max-width: 480px) {
  .a2a-footer-links-5col { grid-template-columns: 1fr; }
}


/* ========== M3 Trust Bar (P0-1) ========== */
section.a2a-trust-bar {
  background: rgba(10,16,28,0.95);
  border-top: 1px solid rgba(255,255,255,0.04);
  border-bottom: 1px solid rgba(255,255,255,0.04);
  padding: 48px 0;
}
.a2a-trust-bar-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
}
.a2a-trust-bar-grid .a2a-trust-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 24px;
  border-right: 1px solid rgba(255,255,255,0.05);
}
.a2a-trust-bar-grid .a2a-trust-item:last-child {
  border-right: none;
}
.a2a-trust-bar-grid .a2a-trust-icon {
  font-size: 24px;
  line-height: 1;
  flex-shrink: 0;
}
.a2a-trust-bar-grid .a2a-trust-text {
  display: flex;
  flex-direction: column;
}
.a2a-trust-bar-grid .a2a-trust-number {
  font-family: "Outfit", sans-serif;
  font-size: 16px;
  font-weight: 700;
  color: var(--gold);
  line-height: 1.3;
}
.a2a-trust-bar-grid .a2a-trust-label {
  font-size: 12px;
  color: var(--text-tertiary);
  line-height: 1.3;
}

/* ========== M4 Partners Wall (P0-2) ========== */
.a2a-partners {
  margin-top: 48px;
  display: flex;
  flex-direction: column;
  gap: 48px;
}
.a2a-partners-group-title {
  font-family: "Outfit", "PingFang SC", sans-serif;
  font-size: 18px;
  font-weight: 700;
  color: rgba(230,194,110,0.8);
  margin-bottom: 24px;
  text-align: center;
}
.a2a-partners-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  row-gap: 32px; column-gap: 24px;
}
.a2a-partner-item {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 10px;
  padding: 14px 16px;
  text-align: center;
  font-family: "Outfit", "PingFang SC", sans-serif;
  font-size: 14px;
  font-weight: 600;
  color: var(--gold);
  transition: all 0.2s ease;
}
.a2a-partner-item:hover {
  border-color: rgba(230,194,110,0.3);
  background: rgba(17,28,48,0.9);
  transform: translateY(-2px);
  box-shadow: 0 8px 32px rgba(0,0,0,0.3);
}

@media (max-width: 768px) {
  .a2a-trust-bar-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 0;
  }
  .a2a-trust-item {
    border-right: none;
    border-bottom: 1px solid rgba(255,255,255,0.05);
    padding: 16px 12px;
  }
  .a2a-trust-item:nth-child(odd) {
    border-right: 1px solid rgba(255,255,255,0.05);
  }
  .a2a-partners-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}



/* --- Logo image --- */
.a2a-logo-img {
  height: 81px;
  width: auto;
  display: block;
}

/* ============================================================
   Layout Alignment Fixes — Hero centering + section constraints
   ============================================================ */

/* --- Hero: two-column layout, visual left --- */
.a2a-hero-grid {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 60px;
  align-items: center;
  text-align: left;
  margin-top: 220px;
}
.a2a-hero-grid > .a2a-animate:first-child {
  max-width: 720px;
}
.a2a-hero-title {
  text-align: left;
  font-size: 66px;
}
.a2a-hero-subtitle {
  text-align: left;
  max-width: none;
  margin: 24px 0 0;
  white-space: nowrap;
}

.a2a-hero-line2 {
  .a2a-hero-title > br + span { display: inline-block; margin-left: 2em; }
  display: inline-block;
  margin-left: 2em;
}
.a2a-hero-actions { margin-top: 40px;
  justify-content: flex-start;
}
.a2a-hero-visual {
  margin-top: 20px;
}

/* --- Section inner: tighter max-width for consistent centering --- */
.a2a-section-inner {
  max-width: 1100px;
  margin: 0 auto 40px;
  padding: 0 40px;
}

/* --- Section titles/labels centered --- */
.a2a-section-label {
  text-align: center;
  display: block;
}
.a2a-section-title {
  text-align: center;
  margin-bottom: 48px;
}
.a2a-section-desc {
  text-align: center;
  margin: 0 auto 40px;
}

/* --- Protocol 3-card stack: centered with max-width --- */
.a2a-protocol-stack {
  max-width: 960px;
  margin: 48px auto 0;
}

/* --- 3-step integration: centered --- */
.a2a-steps {
  max-width: 960px;
  margin: 48px auto 0;
}

/* --- Comparison table: centered --- */
.a2a-comparison-table {
  max-width: 900px;
  margin: 40px auto 0;
}
.a2a-comparison-table th,
.a2a-comparison-table td {
  padding: 16px 20px;
}

/* --- Case studies grid: centered --- */
.a2a-cases-grid {
  max-width: 1100px;
  margin: 48px auto 0;
}

/* --- FAQ grid: centered --- */
.a2a-faq-grid {
  max-width: 900px;
  margin: 40px auto 0;
}

/* --- Dev section: centered --- */
.a2a-dev-grid {
  max-width: 1100px;
  margin: 48px auto 0;
}

/* --- Tech spec grid: centered --- */
.a2a-techspec-grid {
  max-width: 960px;
  margin: 40px auto 0;
}

/* --- Module cards grid: centered --- */
.a2a-modules-grid {
  max-width: 1100px;
  margin: 48px auto 0;
}

/* --- Roadmap timeline: centered --- */
.a2a-roadmap-timeline {
  max-width: 800px;
  margin: 48px auto 0;
}

/* --- Partner wall: centered --- */
.a2a-partners {
  max-width: 1000px;
  margin: 48px auto 0;
}

/* --- Trust bar inner: centered --- */
.a2a-trust-bar .a2a-section-inner {
  max-width: 1100px;
  margin: 0 auto 40px;
}

/* --- Navigation: centered --- */
.a2a-nav-inner {
  max-width: 1200px;
  margin: 0 auto 40px;
  padding: 0 40px;
}

/* --- Responsive: restore some breathing room --- */
@media (max-width: 768px) {
  .a2a-section-inner {
    padding: 0 24px;
    max-width: 100%;
  }
  .a2a-hero-grid > .a2a-animate:first-child {
    max-width: 100%;
  }
  .a2a-hero-subtitle {
    max-width: 100%;
  }
  .a2a-protocol-stack,
  .a2a-steps,
  .a2a-cases-grid,
  .a2a-dev-grid,
  .a2a-techspec-grid,
  .a2a-faq-grid,
  .a2a-comparison-table,
  .a2a-partners,
  .a2a-modules-grid,
  .a2a-roadmap-timeline {
    max-width: 100%;
  }
}

/* ========== Global Section Spacing Overrides ========== */
.a2a-section { padding: 100px 0; }
#a2a-hero { padding: 140px 0 30px; }

/* Grid row/column gaps */
.a2a-modules-grid { row-gap: 32px; column-gap: 24px; }
.a2a-steps { row-gap: 32px; column-gap: 24px; }
.a2a-cases-grid { row-gap: 32px; column-gap: 24px; }
.a2a-faq-grid { row-gap: 32px; column-gap: 24px; }
.a2a-protocol-stack { row-gap: 32px; column-gap: 24px; }

/* Step card inner padding */
.a2a-step { padding: 40px 32px; }
.a2a-step-code { margin-top: 20px; }

/* FAQ item spacing */
.a2a-faq-item { margin-bottom: 20px; }

/* ===== 平板端（768-1024px）===== */
@media (max-width: 1024px) {
  .a2a-nav-links { gap: 14px; font-size: 13px; }
  .a2a-hero-visual { max-width: 260px; margin-top: 30px; }
  .a2a-hero-grid { grid-template-columns: 1fr; gap: 30px; margin-top: 100px; }
  .a2a-hero-visual { margin: 0 auto 20px; max-width: 220px; }
  .a2a-hero-title { font-size: 54px; }
  .a2a-section-inner, .a2a-container { padding: 0 32px; }
  .a2a-protocol-cards { grid-template-columns: 1fr; }
  .a2a-modules-grid { grid-template-columns: repeat(2, 1fr); }
  .a2a-steps { grid-template-columns: 1fr; }
  .a2a-nav-cta { display: none; }
}

/* ===== 手机端（≤768px）===== */
@media (max-width: 768px) {
  /* 导航 */
  .a2a-nav-links { display: none; }
  .a2a-nav-toggle { display: flex; }
  .a2a-nav-toggle.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
  .a2a-nav-toggle.active span:nth-child(2) { opacity: 0; }
  .a2a-nav-toggle.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
  .a2a-nav-links.open {
    display: flex; flex-direction: column; position: absolute;
    top: 60px; left: 0; right: 0; background: var(--bg); padding: 20px; gap: 16px; z-index: 100;
  }
  .a2a-nav-inner { padding: 0 20px; position: relative; }
  .a2a-nav-toggle { position: absolute; left: 0; top: 50%; transform: translateY(-50%); z-index: 101; }
  
  /* Hero */
  .a2a-hero-grid { display: flex; flex-direction: column; margin-top: 40px; }
  .a2a-hero-visual { display: none; }
  .a2a-hero-title { font-size: 42px; line-height: 1.2; text-align: left; }
  .a2a-hero-subtitle { font-size: 14px; max-width: 100%; text-align: left; margin-bottom: 48px; white-space: nowrap; }
  .a2a-hero-actions { margin-top: 0; flex-direction: column; align-items: center; gap: 12px; }
  .a2a-hero-badge { font-size: 12px; }
  
  /* section 统一 */
  .a2a-section, #a2a-protocol, #a2a-modules, #a2a-integration, 
  #a2a-cases, #a2a-roadmap, #a2a-dev, #a2a-faq, #a2a-partners { padding: 60px 0; }
  #a2a-hero { padding: 100px 0 24px; }
  .a2a-section-inner, .a2a-container { padding: 0 20px; }
  .a2a-section-title { font-size: 24px; margin-bottom: 32px; }
  
  /* 信任条 */
  .a2a-trust-bar-grid { grid-template-columns: repeat(2, 1fr); gap: 16px; }
  
  /* 协议卡片 */
  .a2a-protocol-cards { grid-template-columns: 1fr; }
  
  /* 核心模块 */
  .a2a-modules-grid { grid-template-columns: 1fr; }
  
  /* 3步接入 */
  .a2a-steps { grid-template-columns: 1fr; gap: 24px; }
  .a2a-step { padding: 28px 20px; }
  
  /* 案例 */
  .a2a-cases-grid { grid-template-columns: 1fr; }
  
  /* 对比表格 */
  .a2a-comparison-table { font-size: 12px; }
  .a2a-comparison-table td, .a2a-comparison-table th { padding: 10px 8px; }
  
  /* 技术规格 */
  .a2a-tech-grid { grid-template-columns: 1fr; }
  
  /* 路线图 */
  .a2a-timeline { padding-left: 20px; }
  
  /* 合作伙伴 */
  .a2a-partners-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }
  .a2a-partner-item { padding: 12px 8px; font-size: 12px; }
  
  /* FAQ */
  .a2a-faq-grid { grid-template-columns: 1fr; }
  
  /* Footer */
  .a2a-footer-grid { grid-template-columns: repeat(2, 1fr); gap: 24px; }
  .a2a-trust-anchors { grid-template-columns: repeat(2, 1fr); gap: 12px; }
  
  /* Logo */
  .a2a-logo-img { height: 60px; }
}

/* ===== 小屏手机（≤480px）===== */
@media (max-width: 480px) {
  .a2a-hero-title { font-size: 36px; line-height: 1.2; text-align: left; }
  .a2a-trust-bar-grid { grid-template-columns: 1fr; }
  .a2a-partners-grid { grid-template-columns: repeat(2, 1fr); }
  .a2a-footer-grid { grid-template-columns: 1fr; }
}
/* ==================== V2.1 + V2.2 Incremental CSS ==================== */

/* D1: Digital Assets Section */
.a2a-digital-assets { padding: 0 0 80px; }
.a2a-asset-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 24px; margin-top: 40px; }
.a2a-asset-card { background: rgba(230,194,110,0.04); border: 1px solid rgba(230,194,110,0.12); border-radius: 12px; padding: 28px; transition: border-color 0.3s, transform 0.3s; }
.a2a-asset-card:hover { border-color: rgba(230,194,110,0.3); transform: translateY(-2px); }
.a2a-asset-card-icon { font-size: 32px; margin-bottom: 12px; }
.a2a-asset-card h4 { font-size: 18px; color: var(--gold); margin-bottom: 8px; }
.a2a-asset-card p { font-size: 14px; color: var(--text-primary); line-height: 1.6; }
.a2a-asset-card .a2a-asset-tags { margin-top: 12px; display: flex; flex-wrap: wrap; gap: 6px; }
.a2a-asset-tag { font-size: 11px; padding: 3px 10px; border-radius: 20px; background: rgba(74,144,226,0.15); color: #4A90E2; border: 1px solid rgba(74,144,226,0.2); }

/* D1 Business Value */
.a2a-asset-value { margin-top: 48px; padding: 32px; background: linear-gradient(135deg, rgba(230,194,110,0.08), rgba(74,144,226,0.06)); border-radius: 12px; border: 1px solid rgba(230,194,110,0.15); }
.a2a-asset-value h3 { font-size: 20px; color: var(--gold); margin-bottom: 16px; }
.a2a-asset-value-list { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 16px; }
.a2a-asset-value-item { display: flex; align-items: flex-start; gap: 10px; font-size: 14px; color: var(--text-primary); line-height: 1.6; }
.a2a-asset-value-item .a2a-v-icon { color: #7CC576; font-size: 16px; flex-shrink: 0; margin-top: 2px; }

/* Case Cards (C1, C2) */
.a2a-case-highlight { background: linear-gradient(135deg, rgba(230,194,110,0.06), rgba(74,144,226,0.04)); border: 1px solid rgba(230,194,110,0.2); }
.a2a-case-metrics { display: flex; gap: 16px; flex-wrap: wrap; margin-top: 12px; }
.a2a-case-metric { font-size: 13px; padding: 4px 12px; border-radius: 20px; background: rgba(74,144,226,0.12); color: #4A90E2; }

/* R1: Data Roadmap */
.a2a-data-roadmap { padding: 0 0 80px; }
.a2a-roadmap-timeline { position: relative; margin-top: 40px; padding-left: 40px; }
.a2a-roadmap-timeline::before { content: ''; position: absolute; left: 14px; top: 0; bottom: 0; width: 2px; background: linear-gradient(to bottom, var(--gold), #4A90E2); }
.a2a-roadmap-phase { position: relative; margin-bottom: 36px; }
.a2a-roadmap-phase::before { content: ''; position: absolute; left: -33px; top: 6px; width: 12px; height: 12px; border-radius: 50%; background: var(--gold); border: 2px solid var(--bg); }
.a2a-roadmap-phase h4 { font-size: 18px; color: var(--gold); margin-bottom: 6px; }
.a2a-roadmap-phase .a2a-phase-label { font-size: 12px; color: var(--text-primary); margin-bottom: 8px; }
.a2a-roadmap-phase p { font-size: 14px; color: var(--text-secondary); line-height: 1.7; }

/* B1: Dual Pricing */
.a2a-pricing-dual { padding: 0 0 80px; }
.a2a-pricing-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 24px; margin-top: 40px; }
.a2a-pricing-card { background: rgba(230,194,110,0.04); border: 1px solid rgba(230,194,110,0.12); border-radius: 12px; padding: 32px; text-align: center; }
.a2a-pricing-card.featured { border-color: rgba(230,194,110,0.35); background: linear-gradient(135deg, rgba(230,194,110,0.08), rgba(74,144,226,0.04)); }
.a2a-pricing-card h4 { font-size: 20px; color: var(--gold); margin-bottom: 4px; }
.a2a-pricing-card .a2a-price-tag { font-size: 14px; color: var(--text-secondary); margin-bottom: 16px; }
.a2a-pricing-card .a2a-price-rate { font-size: 36px; font-weight: 700; color: var(--gold); margin-bottom: 4px; }
.a2a-pricing-card .a2a-price-desc { font-size: 13px; color: var(--text-primary); margin-bottom: 20px; }
.a2a-pricing-features { list-style: none; padding: 0; text-align: left; }
.a2a-pricing-features li { font-size: 14px; color: var(--text-secondary); padding: 8px 0; border-bottom: 1px solid rgba(255,255,255,0.05); display: flex; align-items: center; gap: 8px; }
.a2a-pricing-features li::before { content: '✓'; color: #7CC576; font-weight: 700; }

/* P2: AP2 x402 Upgrade */
.a2a-protocol-card.highlight { border-color: rgba(230,194,110,0.3); background: linear-gradient(135deg, rgba(230,194,110,0.06), rgba(74,144,226,0.04)); }
.a2a-protocol-tag { display: inline-block; font-size: 11px; padding: 3px 10px; border-radius: 20px; background: rgba(74,144,226,0.12); color: #4A90E2; border: 1px solid rgba(74,144,226,0.2); margin: 3px; }
.a2a-protocol-detail { margin-top: 12px; font-size: 13px; color: #7CC576; }

/* P3: 4 Capabilities + A2A vs MCP */
.a2a-cap-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 20px; margin: 32px 0; }
.a2a-cap-card { background: rgba(230,194,110,0.04); border: 1px solid rgba(230,194,110,0.1); border-radius: 10px; padding: 24px; text-align: center; }
.a2a-cap-card .a2a-cap-icon { font-size: 28px; margin-bottom: 10px; }
.a2a-cap-card h4 { font-size: 16px; color: var(--gold); margin-bottom: 6px; }
.a2a-cap-card p { font-size: 13px; color: var(--text-secondary); line-height: 1.5; }
.a2a-vs-mcp { margin-top: 32px; overflow-x: auto; }
.a2a-vs-mcp table { width: 100%; border-collapse: collapse; font-size: 13px; }
.a2a-vs-mcp th { background: rgba(230,194,110,0.12); color: var(--gold); padding: 10px 14px; text-align: left; border-bottom: 1px solid rgba(230,194,110,0.15); }
.a2a-vs-mcp td { padding: 10px 14px; border-bottom: 1px solid rgba(255,255,255,0.05); color: var(--text-primary); }
.a2a-vs-mcp tr:hover td { background: rgba(230,194,110,0.03); }

/* P4: SDK/Frameworks */
.a2a-dev-category { margin-bottom: 32px; }
.a2a-dev-category h3 { font-size: 18px; color: var(--gold); margin-bottom: 14px; padding-bottom: 8px; border-bottom: 1px solid rgba(230,194,110,0.12); }
.a2a-sdk-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 12px; }
.a2a-sdk-card { background: rgba(230,194,110,0.04); border: 1px solid rgba(230,194,110,0.1); border-radius: 8px; padding: 16px; text-align: center; transition: border-color 0.3s; }
.a2a-sdk-card:hover { border-color: rgba(230,194,110,0.25); }
.a2a-sdk-card .a2a-sdk-name { font-size: 15px; font-weight: 600; color: var(--gold); }
.a2a-sdk-card .a2a-sdk-desc { font-size: 12px; color: var(--text-tertiary); margin-top: 4px; }
.a2a-framework-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 10px; }
.a2a-framework-card { background: rgba(74,144,226,0.06); border: 1px solid rgba(74,144,226,0.12); border-radius: 8px; padding: 14px; text-align: center; font-size: 13px; color: var(--text-secondary); transition: border-color 0.3s; }
.a2a-framework-card:hover { border-color: rgba(74,144,226,0.3); }

/* P5: Graduation Protocol */
.a2a-graduation { padding: 0 0 80px; }
.a2a-grad-timeline { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 0; position: relative; margin-top: 40px; }
.a2a-grad-phase { padding: 28px 24px; text-align: center; position: relative; }
.a2a-grad-phase:not(:last-child)::after { content: '→'; position: absolute; right: -8px; top: 50%; transform: translateY(-50%); font-size: 24px; color: var(--gold); z-index: 1; }
.a2a-grad-phase .a2a-grad-num { width: 48px; height: 48px; border-radius: 50%; background: linear-gradient(135deg, var(--gold), #4A90E2); display: flex; align-items: center; justify-content: center; font-size: 20px; font-weight: 700; color: var(--bg); margin: 0 auto 16px; }
.a2a-grad-phase h4 { font-size: 18px; color: var(--gold); margin-bottom: 8px; }
.a2a-grad-phase p { font-size: 13px; color: var(--text-secondary); line-height: 1.6; }
.a2a-grad-badge { display: inline-flex; align-items: center; gap: 6px; padding: 6px 16px; border-radius: 20px; background: linear-gradient(135deg, rgba(230,194,110,0.15), rgba(74,144,226,0.1)); border: 1px solid rgba(230,194,110,0.3); font-size: 13px; color: var(--gold); margin-top: 24px; }
.a2a-grad-conditions { margin-top: 32px; display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; }
.a2a-grad-condition { padding: 16px; border: 1px solid rgba(230,194,110,0.1); border-radius: 8px; text-align: center; }
.a2a-grad-condition .a2a-gc-num { font-size: 28px; font-weight: 700; color: var(--gold); }
.a2a-grad-condition .a2a-gc-label { font-size: 13px; color: var(--text-secondary); margin-top: 4px; }

/* P6: Agent Self-Service */
.a2a-self-service { padding: 0 0 80px; }
.a2a-self-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 24px; margin-top: 40px; }
.a2a-self-card { background: rgba(230,194,110,0.04); border: 1px solid rgba(230,194,110,0.12); border-radius: 12px; padding: 28px; }
.a2a-self-card h4 { font-size: 18px; color: var(--gold); margin-bottom: 8px; }
.a2a-self-card p { font-size: 13px; color: var(--text-secondary); line-height: 1.6; margin-bottom: 12px; }
.a2a-self-card .a2a-code-block { font-size: 11px; background: rgba(0,0,0,0.3); padding: 12px; border-radius: 6px; overflow-x: auto; color: var(--text-primary); font-family: 'JetBrains Mono', monospace; }

/* E2: Compliance (already partially in footer) */
.a2a-compliance { padding: 0 0 80px; }
.a2a-compliance-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 20px; margin-top: 40px; }
.a2a-compliance-card { text-align: center; padding: 28px; background: rgba(230,194,110,0.04); border: 1px solid rgba(230,194,110,0.12); border-radius: 12px; }
.a2a-compliance-card .a2a-comp-icon { font-size: 36px; margin-bottom: 12px; }
.a2a-compliance-card h4 { font-size: 16px; color: var(--gold); margin-bottom: 6px; }
.a2a-compliance-card p { font-size: 13px; color: var(--text-secondary); }

/* Trust Bar (M3 upgrade) */
.a2a-trust-bar { padding: 24px 0; border-top: 1px solid rgba(230,194,110,0.08); border-bottom: 1px solid rgba(230,194,110,0.08); background: rgba(230,194,110,0.03); }
.a2a-trust-label { text-align: center; font-size: 13px; color: var(--text-secondary); margin-bottom: 16px; }
.a2a-trust-logos { display: flex; flex-wrap: wrap; justify-content: center; gap: 20px; margin-bottom: 16px; }
.a2a-trust-logo { font-size: 14px; font-weight: 600; color: var(--text-secondary); padding: 8px 16px; border: 1px solid rgba(230,194,110,0.15); border-radius: 6px; background: rgba(230,194,110,0.04); }
.a2a-trust-foot { text-align: center; font-size: 12px; color: var(--text-tertiary); }

/* Partners Grid */
.a2a-partner-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 16px; margin-top: 32px; }
.a2a-partner-card { text-align: center; padding: 18px 12px; border: 1px solid rgba(230,194,110,0.1); border-radius: 8px; background: rgba(230,194,110,0.03); font-size: 14px; color: var(--text-secondary); transition: border-color 0.3s; }
.a2a-partner-card:hover { border-color: rgba(230,194,110,0.25); }

/* P1 Trust Bar upgrade - governance badge */
.a2a-gov-badge { display: inline-flex; align-items: center; gap: 6px; padding: 6px 14px; border-radius: 20px; background: rgba(74,144,226,0.12); border: 1px solid rgba(74,144,226,0.2); font-size: 12px; color: #4A90E2; margin: 0 6px; }

/* Responsive: P5 Graduation arrows */
@media (max-width: 768px) {
  .a2a-grad-phase:not(:last-child)::after { content: '↓'; right: 50%; top: auto; bottom: -12px; transform: translateX(50%); }
  .a2a-grad-timeline { grid-template-columns: 1fr; }
  .a2a-trust-logos { gap: 10px; }
  .a2a-trust-logo { font-size: 12px; padding: 6px 10px; }
}

/* ==================== End V2.1 + V2.2 CSS ==================== */

/* ============================================================
   V3.0 Mobile Optimization — Hero, Cards, Buttons, Safe Area
   ============================================================ */

@media (max-width: 768px) {
  /* ---- Nav ---- */
  .a2a-nav-inner { padding: 0 16px; height: 56px; }
  .a2a-logo { font-size: 23px; }
  .a2a-logo-img { height: 54px; }

  /* ---- Hero: spacing rebalance ---- */
  #a2a-hero { padding: 120px 0 30px; }
  .a2a-hero-grid {
    display: flex;
    flex-direction: column;
    margin-top: 36px;
    gap: 28px;
  }

  /* Hero title: keep "自主协作" together */
  .a2a-hero-title {
    font-size: 36px;
    line-height: 1.25;
    text-align: left;
    margin-bottom: 12px;
  }
  .a2a-hero-title .gold {
    white-space: nowrap;
  }

  /* Hero subtitle: constrained width + better line-height */
  .a2a-hero-subtitle {
    font-size: 14px;
    line-height: 1.75;
    max-width: 100%;
    text-align: left;
    margin-bottom: 28px;
    color: var(--text-secondary);
    white-space: nowrap;
  }

  /* Hero badge */
  .a2a-hero-badge {
    font-size: 12px;
    padding: 5px 14px;
    margin-bottom: 16px;
  }

  /* ---- CTA Buttons: 48px touch, 16px gap, hierarchy ---- */
  .a2a-hero-actions {
    margin-top: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 16px;
  }
  .a2a-hero-actions .a2a-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    width: 100%;
    font-size: 15px;
    padding: 14px 28px;
    border-radius: 28px;
    text-align: center;
    box-sizing: border-box;
  }
  /* Primary: solid gold */
  .a2a-hero-actions .a2a-btn-primary {
    background: var(--gold-gradient);
    color: var(--bg);
    border: none;
    font-weight: 700;
  }
  .a2a-hero-actions .a2a-btn-outline {
    background: transparent;
    border: 2px solid var(--text-tertiary);
    color: var(--text-secondary);
    font-weight: 600;
  }

  /* ---- Hero Visual: hidden on mobile ---- */
  .a2a-hero-visual { display: none; }

  /* ---- Sections: card containers + spacing ---- */
  .a2a-section {
    padding: 60px 0;
  }
  .a2a-section-inner {
    padding: 0 20px;
    max-width: 100%;
  }

  /* Section visual separators */
  .a2a-section:not(#a2a-hero):not(.a2a-trust-bar) {
    margin: 0 12px 24px;
    border-radius: 16px;
    background: rgba(13,21,37,0.4);
    padding: 48px 0;
  }

  .a2a-section-title {
    font-size: 24px;
    margin-bottom: 32px;
  }
  .a2a-section-desc {
    font-size: 14px;
    line-height: 1.7;
    max-width: 100%;
    padding: 0 4px;
    margin-bottom: 32px;
  }

  /* ---- Trust bar ---- */
  .a2a-trust-bar-grid { grid-template-columns: repeat(2, 1fr); gap: 0; }
  .a2a-trust-bar-grid .a2a-trust-item {
    padding: 14px 10px;
    gap: 10px;
  }
  .a2a-trust-bar-grid .a2a-trust-number { font-size: 14px; }
  .a2a-trust-bar-grid .a2a-trust-label { font-size: 11px; }

  /* ---- Protocol / Modules / Steps ---- */
  .a2a-protocol-stack, .a2a-modules-grid, .a2a-steps,
  .a2a-cases-grid, .a2a-faq-grid, .a2a-techspec-grid {
    grid-template-columns: 1fr;
    max-width: 100%;
  }

  .a2a-protocol-layer { padding: 28px 20px; }
  .a2a-module-card { padding: 24px 20px; }
  .a2a-step { padding: 28px 20px; }

  /* ---- Comparison table ---- */
  .a2a-comparison-table { font-size: 12px; }
  .a2a-comparison-table th, .a2a-comparison-table td { padding: 10px 8px; }
  .a2a-comparison-table td:first-child { width: 80px; white-space: normal; }

  /* ---- Partners ---- */
  .a2a-partners-grid { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .a2a-partner-item { padding: 12px 8px; font-size: 12px; }

  /* ---- Roadmap ---- */
  .a2a-roadmap-timeline { padding-left: 28px; max-width: 100%; }
  .a2a-roadmap-phase { padding-left: 16px; }
  .a2a-roadmap-phase::before { left: -25px; }

  /* ---- Footer ---- */
  #a2a-footer { padding-bottom: 0; }
  .a2a-footer-cta { padding: 48px 20px; }
  .a2a-footer-cta h2 { font-size: 24px; }
  .a2a-footer-cta-actions {
    flex-direction: column;
    align-items: stretch;
    gap: 14px;
  }
  .a2a-footer-cta-actions .a2a-btn {
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
  }
  .a2a-footer-links-5col { grid-template-columns: repeat(2, 1fr); gap: 20px; padding: 32px 20px; }
  .a2a-footer-col h4 { font-size: 12px; }
  .a2a-footer-col a { font-size: 12px; }

  /* ---- Trust anchors ---- */
  .a2a-trust-anchors { grid-template-columns: repeat(2, 1fr); gap: 10px; padding: 24px 16px; margin-bottom: 24px; }
  .a2a-trust-anchor-card { padding: 16px 12px; min-width: 0; }

  /* ---- Footer subscribe ---- */
  .a2a-footer-subscribe { padding: 0 20px; flex-direction: column; gap: 10px; max-width: 100%; }
  .a2a-footer-subscribe input { width: 100%; }

  /* ---- Footer bottom ---- */
  .a2a-footer-bottom { padding: 16px 20px; font-size: 11px; }
  .a2a-footer-bottom-links { gap: 10px; }

  /* ---- Safe area for bottom nav ---- */
  .a2a-footer-bottom {
    padding-bottom: max(16px, env(safe-area-inset-bottom, 16px));
  }

  /* ---- Scroll to top ---- */
  .a2a-scroll-top {
    bottom: max(20px, calc(env(safe-area-inset-bottom, 0px) + 16px));
    right: 20px;
    width: 40px;
    height: 40px;
    font-size: 18px;
  }

  /* ---- Section card separation for non-hero sections ---- */
  .a2a-section-inner > .a2a-animate:first-child {
    margin-top: 0;
  }

  /* Pricing cards */
  .a2a-pricing-grid { grid-template-columns: 1fr; margin-top: 32px; }
  .a2a-pricing-card { padding: 28px 24px; }
  .a2a-pricing-card .a2a-price-rate { font-size: 30px; }

  /* Digital assets */
  .a2a-asset-grid { grid-template-columns: 1fr; }
  .a2a-asset-value-list { grid-template-columns: 1fr; }
  .a2a-asset-value { padding: 24px 20px; }

  /* Self-service */
  .a2a-self-grid { grid-template-columns: 1fr; }

  /* Cap grid */
  .a2a-cap-grid { grid-template-columns: 1fr; }

  /* Compliance */
  .a2a-compliance-grid { grid-template-columns: 1fr; }

  /* Dev section */
  .a2a-dev-grid { grid-template-columns: 1fr; }

  /* SDK */
  .a2a-sdk-grid { grid-template-columns: repeat(2, 1fr); }
}

/* ---- 480px extra narrow ---- */
@media (max-width: 480px) {
  .a2a-hero-title { font-size: 30px; }
  .a2a-hero-visual { min-height: 240px; padding: 14px; }
  .a2a-hero-glow { width: 160px; height: 160px; }
  .a2a-hero-nodes { width: 160px; height: 160px; }
  .a2a-hero-node { width: 36px; height: 36px; font-size: 15px; }
  .a2a-hero-node.center { width: 46px; height: 46px; font-size: 12px; }

  .a2a-trust-bar-grid { grid-template-columns: 1fr; }
  .a2a-partners-grid { grid-template-columns: repeat(2, 1fr); }
  .a2a-footer-links-5col { grid-template-columns: 1fr; }
  .a2a-trust-anchors { grid-template-columns: 1fr; }
  .a2a-sdk-grid { grid-template-columns: 1fr; }
}

/* ---- Section card containers (tablet + desktop subtle) ---- */
@media (min-width: 769px) and (max-width: 1024px) {
  .a2a-section:not(#a2a-hero):not(.a2a-trust-bar) {
    margin: 0 16px 32px;
    border-radius: 16px;
    background: rgba(13,21,37,0.3);
    padding: 64px 0;
  }
}