/* ===== RESET & BASE ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body { min-height: 100vh; line-height: 1.6; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }
img, picture, video, canvas, svg { display: block; max-width: 100%; }
input, button, textarea, select { font: inherit; color: inherit; }
button { cursor: pointer; border: none; background: none; }
ul, ol { list-style: none; }
a { color: inherit; text-decoration: none; }
a:focus-visible, button:focus-visible { outline: 2px solid #FF6B35; outline-offset: 2px; }
:focus:not(:focus-visible) { outline: none; }
::selection { background: #2E8B57; color: #fff; }

/* ===== CSS VARIABLES ===== */
:root {
  --color-primary: #2E8B57;
  --color-primary-hover: #3ca06a;
  --color-accent: #FF6B35;
  --color-accent-hover: #e85a2a;
  --color-bg: #1A1A1A;
  --color-surface: #2A2A2A;
  --color-surface-hover: #353535;
  --color-text: #FFFFFF;
  --color-text-secondary: #B0B0B0;
  --color-highlight: #FFD700;
  --color-error: #FF4444;
  --color-border: rgba(255,255,255,0.10);
  --color-border-strong: rgba(255,255,255,0.20);

  --font-heading: Impact, Haettenschweiler, 'Arial Black', sans-serif;
  --font-body: Georgia, 'Times New Roman', serif;
  --font-size-h1: 48px;
  --font-size-h2: 36px;
  --font-size-h3: 24px;
  --font-size-body: 16px;
  --line-height-body: 1.6;

  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;
  --spacing-3xl: 64px;

  --max-width: 1200px;
  --header-height: 140px;
  --header-scroll-offset: 80px;

  --transition: 0.3s ease;
  --transition-fast: 0.15s ease;
}

/* ===== SKIP LINK ===== */
.skip-link {
  position: fixed;
  top: -100%;
  left: var(--spacing-md);
  z-index: 9999;
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--color-accent);
  color: #fff;
  font-family: var(--font-heading);
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 1px;
  border-radius: 0 0 4px 4px;
  transition: top var(--transition);
}
.skip-link:focus {
  top: 0;
  outline: 2px solid #fff;
  outline-offset: -2px;
}

/* ===== HEADER ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  font-family: var(--font-heading);
}
.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}
.header-top {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-lg) 0 var(--spacing-md);
  position: relative;
}
.brand-link {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  text-decoration: none;
  transition: opacity var(--transition-fast);
}
.brand-link:hover { opacity: 0.85; }
.brand-icon {
  font-size: 32px;
  line-height: 1;
}
.brand-name {
  font-size: 28px;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: 1px;
  text-transform: uppercase;
  line-height: 1.1;
}
.brand-sublabel {
  display: none;
  font-size: 12px;
  color: var(--color-text-secondary);
  letter-spacing: 3px;
  text-transform: uppercase;
  margin-left: var(--spacing-sm);
  padding-left: var(--spacing-sm);
  border-left: 1px solid var(--color-border-strong);
  line-height: 1;
  align-self: flex-end;
  padding-bottom: 2px;
}
.header-actions {
  position: absolute;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}
.action-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  color: var(--color-text-secondary);
  border-radius: 0;
  transition: color var(--transition-fast), background var(--transition-fast);
}
.action-btn:hover { color: var(--color-primary); background: var(--color-surface); }
.action-btn svg { width: 20px; height: 20px; }

/* ===== NAVIGATION ===== */
.site-nav { border-top: 1px solid var(--color-border); }
.nav-list {
  display: flex;
  justify-content: center;
  gap: 0;
}
.nav-link {
  display: block;
  padding: var(--spacing-md) var(--spacing-lg);
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--color-text-secondary);
  transition: color var(--transition-fast), background var(--transition-fast);
  position: relative;
  white-space: nowrap;
}
.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: var(--spacing-lg);
  right: var(--spacing-lg);
  height: 2px;
  background: var(--color-primary);
  transform: scaleX(0);
  transition: transform var(--transition);
}
.nav-link:hover { color: var(--color-primary); background: var(--color-surface); }
.nav-link:hover::after { transform: scaleX(1); }
.nav-link[aria-current="page"] {
  color: var(--color-primary);
}
.nav-link[aria-current="page"]::after {
  transform: scaleX(1);
  background: var(--color-accent);
  height: 3px;
}

/* ===== NAV TOGGLE (mobile) ===== */
.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  color: var(--color-text);
  background: var(--color-surface);
  border-radius: 0;
  transition: background var(--transition-fast);
}
.nav-toggle:hover { background: var(--color-surface-hover); }
.nav-toggle-icon {
  display: block;
  width: 22px;
  height: 2px;
  background: currentColor;
  position: relative;
  transition: background var(--transition-fast);
}
.nav-toggle-icon::before,
.nav-toggle-icon::after {
  content: '';
  position: absolute;
  left: 0;
  width: 22px;
  height: 2px;
  background: currentColor;
  transition: transform var(--transition);
}
.nav-toggle-icon::before { top: -7px; }
.nav-toggle-icon::after { top: 7px; }
[data-nav-toggle][aria-expanded="true"] .nav-toggle-icon { background: transparent; }
[data-nav-toggle][aria-expanded="true"] .nav-toggle-icon::before { transform: translateY(7px) rotate(45deg); }
[data-nav-toggle][aria-expanded="true"] .nav-toggle-icon::after { transform: translateY(-7px) rotate(-45deg); }

/* ===== MOBILE NAV ===== */
@media (max-width: 768px) {
  :root { --header-height: 100px; }
  .header-top { padding: var(--spacing-md) 0; }
  .brand-name { font-size: 22px; }
  .brand-icon { font-size: 26px; }
  .header-actions { gap: 2px; }
  .action-btn { width: 36px; height: 36px; }
  .action-btn svg { width: 18px; height: 18px; }
  .nav-toggle { display: flex; }
  .site-nav {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease, opacity 0.3s ease, border-color 0.3s ease;
    opacity: 0;
    border-top-color: transparent;
  }
  .site-nav[data-open] {
    max-height: 500px;
    opacity: 1;
    border-top-color: var(--color-border);
  }
  .nav-list {
    flex-direction: column;
    padding: var(--spacing-sm) 0 var(--spacing-lg);
    gap: 2px;
  }
  .nav-link {
    padding: var(--spacing-md) var(--spacing-md);
    text-align: center;
    font-size: 14px;
  }
  .nav-link::after { display: none; }
  .nav-link[aria-current="page"] {
    background: var(--color-surface);
    border-left: 3px solid var(--color-accent);
  }
}

@media (min-width: 769px) {
  .site-nav { display: block !important; opacity: 1 !important; max-height: none !important; }
  .brand-sublabel { display: inline-block; }
}

/* ===== FOOTER ===== */
.site-footer {
  background: var(--color-bg);
  border-top: 2px solid var(--color-primary);
  font-family: var(--font-body);
  color: var(--color-text-secondary);
  font-size: 14px;
  line-height: 1.7;
}
.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--spacing-2xl) var(--spacing-lg) var(--spacing-lg);
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--spacing-xl);
  padding-bottom: var(--spacing-xl);
  border-bottom: 1px solid var(--color-border);
}
.footer-col-brand { max-width: 360px; }
.footer-logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}
.footer-logo-icon { font-size: 24px; }
.footer-logo-text {
  font-family: var(--font-heading);
  font-size: 20px;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 1px;
}
.footer-description {
  font-size: 13px;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-md);
}
.footer-trust {
  font-size: 12px;
  color: var(--color-text-secondary);
  opacity: 0.75;
  font-style: italic;
  line-height: 1.6;
}
.footer-heading {
  font-family: var(--font-heading);
  font-size: 14px;
  color: var(--color-text);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  margin-bottom: var(--spacing-md);
  padding-bottom: var(--spacing-xs);
  border-bottom: 2px solid var(--color-primary);
  display: inline-block;
}
.footer-link-list li,
.footer-contact-list li,
.footer-legal-links li {
  margin-bottom: var(--spacing-sm);
}
.footer-link-list a,
.footer-legal-links a {
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
  font-size: 13px;
}
.footer-link-list a:hover,
.footer-legal-links a:hover {
  color: var(--color-primary);
}
.footer-contact-list li {
  font-size: 13px;
  display: flex;
  flex-wrap: wrap;
}
.contact-label {
  color: var(--color-text);
  font-weight: 700;
  margin-right: var(--spacing-xs);
}
.footer-contact-list a {
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}
.footer-contact-list a:hover { color: var(--color-primary); }
.footer-legal-links a {
  font-family: var(--font-heading);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
.footer-bottom {
  padding-top: var(--spacing-lg);
  text-align: center;
}
.footer-copyright {
  font-size: 12px;
  color: var(--color-text-secondary);
  opacity: 0.7;
  font-family: var(--font-body);
}
@media (max-width: 900px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--spacing-lg); }
  .footer-col-brand { grid-column: 1 / -1; max-width: none; }
}
@media (max-width: 540px) {
  .footer-grid { grid-template-columns: 1fr; gap: var(--spacing-lg); }
  .footer-col-brand { grid-column: 1; }
  .footer-bottom { text-align: left; }
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: 12px 28px;
  font-family: var(--font-heading);
  font-size: 14px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  border: none;
  border-radius: 0;
  cursor: pointer;
  transition: background var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
  line-height: 1.2;
  text-decoration: none;
}
.btn:active { transform: scale(0.97); }
.btn-primary {
  background: var(--color-primary);
  color: #fff;
}
.btn-primary:hover { background: var(--color-primary-hover); box-shadow: 0 4px 16px rgba(46,139,87,0.3); }
.btn-accent {
  background: var(--color-accent);
  color: #fff;
}
.btn-accent:hover { background: var(--color-accent-hover); box-shadow: 0 4px 16px rgba(255,107,53,0.3); }
.btn-outline {
  background: transparent;
  color: var(--color-text);
  border: 2px solid var(--color-border-strong);
}
.btn-outline:hover { background: var(--color-surface); border-color: var(--color-primary); color: var(--color-primary); }
.btn-sm { padding: 8px 18px; font-size: 12px; }
.btn-lg { padding: 16px 36px; font-size: 16px; }

/* ===== BREADCRUMB ===== */
.breadcrumb {
  font-family: var(--font-heading);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--color-text-secondary);
  padding: var(--spacing-md) 0;
}
.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
  align-items: center;
}
.breadcrumb li { display: flex; align-items: center; gap: var(--spacing-xs); }
.breadcrumb li + li::before {
  content: '/';
  color: var(--color-primary);
  font-weight: 700;
  margin: 0 var(--spacing-xs);
}
.breadcrumb a { color: var(--color-text-secondary); transition: color var(--transition-fast); }
.breadcrumb a:hover { color: var(--color-primary); }
.breadcrumb [aria-current="page"] { color: var(--color-text); }

/* ===== CONTENT CONTAINER ===== */
.content-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}
.content-container-narrow {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

/* ===== GRID SYSTEM ===== */
.grid {
  display: grid;
  gap: var(--spacing-lg);
}
.grid-2 { grid-template-columns: 1fr 1fr; }
.grid-3 { grid-template-columns: 1fr 1fr 1fr; }
.grid-4 { grid-template-columns: 1fr 1fr 1fr 1fr; }
@media (max-width: 900px) {
  .grid-3 { grid-template-columns: 1fr 1fr; }
  .grid-4 { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 540px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

/* ===== IMAGE CONTAINER ===== */
.image-container {
  position: relative;
  overflow: hidden;
  background: var(--color-surface);
  width: 100%;
}
.image-container img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.image-container .image-placeholder {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  font-family: var(--font-heading);
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 1px;
  background: var(--color-surface);
}
.ratio-16-9 { padding-bottom: 56.25%; }
.ratio-4-3 { padding-bottom: 75%; }
.ratio-1-1 { padding-bottom: 100%; }
.ratio-3-2 { padding-bottom: 66.67%; }

/* ===== SECTION NUMBER (编号章节) ===== */
.section-number {
  font-family: var(--font-heading);
  font-size: 80px;
  line-height: 1;
  color: var(--color-primary);
  opacity: 0.25;
  user-select: none;
  pointer-events: none;
  letter-spacing: -2px;
}
@media (max-width: 768px) {
  .section-number { font-size: 52px; }
}

/* ===== ACCORDION ===== */
.accordion {
  border-bottom: 1px solid var(--color-border);
}
.accordion-toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: var(--spacing-md) var(--spacing-sm);
  font-family: var(--font-heading);
  font-size: 16px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--color-text);
  background: none;
  border: none;
  border-top: 1px solid var(--color-border);
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
  text-align: left;
}
.accordion-toggle:hover { background: var(--color-surface); color: var(--color-primary); }
.accordion-toggle::after {
  content: '+';
  font-size: 22px;
  font-weight: 700;
  color: var(--color-accent);
  transition: transform var(--transition);
  flex-shrink: 0;
  margin-left: var(--spacing-md);
}
.accordion[data-open] .accordion-toggle::after {
  content: '−';
  transform: rotate(0deg);
}
.accordion-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.4s ease, opacity 0.3s ease;
  opacity: 0;
  padding: 0 var(--spacing-sm);
}
.accordion[data-open] .accordion-content {
  max-height: 600px;
  opacity: 1;
  padding: var(--spacing-sm) var(--spacing-sm) var(--spacing-lg);
}
.accordion-content p,
.accordion-content li {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* ===== SCROLL TOP ===== */
.scroll-top {
  position: fixed;
  bottom: var(--spacing-lg);
  right: var(--spacing-lg);
  z-index: 900;
  width: 48px;
  height: 48px;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: opacity var(--transition), visibility var(--transition), transform var(--transition), background var(--transition-fast);
  box-shadow: 0 4px 16px rgba(0,0,0,0.4);
}
.scroll-top[data-visible] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.scroll-top:hover { background: var(--color-accent); }
.scroll-top svg { width: 22px; height: 22px; }

/* ===== UTILITY ===== */
.text-center { text-align: center; }
.text-primary { color: var(--color-primary); }
.text-accent { color: var(--color-accent); }
.text-secondary { color: var(--color-text-secondary); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }
.py-lg { padding-top: var(--spacing-lg); padding-bottom: var(--spacing-lg); }
.py-xl { padding-top: var(--spacing-xl); padding-bottom: var(--spacing-xl); }

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  :root {
    --font-size-h1: 32px;
    --font-size-h2: 26px;
    --font-size-h3: 20px;
  }
  .content-container { padding: 0 var(--spacing-md); }
  .content-container-narrow { padding: 0 var(--spacing-md); }
  .scroll-top { bottom: var(--spacing-md); right: var(--spacing-md); width: 42px; height: 42px; }
}

@media (min-width: 769px) and (max-width: 1024px) {
  .content-container { padding: 0 var(--spacing-xl); }
}

/* ===== REDUCED MOTION ===== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  .skip-link { transition: none; }
  .site-nav { transition: none; }
  .accordion-content { transition: none; }
  .scroll-top { transition: none; }
}

/* ===== FOCUS VISIBLE (global) ===== */
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* ===== HEADER TRAJECTORY LINES (足球轨迹装饰) ===== */
.site-header::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  pointer-events: none;
  z-index: -1;
  background:
    linear-gradient(135deg, transparent 40%, rgba(46,139,87,0.06) 40%, rgba(46,139,87,0.06) 42%, transparent 42%),
    linear-gradient(225deg, transparent 55%, rgba(255,107,53,0.05) 55%, rgba(255,107,53,0.05) 57%, transparent 57%),
    linear-gradient(45deg, transparent 70%, rgba(255,215,0,0.04) 70%, rgba(255,215,0,0.04) 72%, transparent 72%);
}
.site-header { position: relative; overflow: hidden; }

/* ===== FOOTER trajectory accent ===== */
.site-footer::before {
  content: '';
  display: block;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent), var(--color-primary));
  width: 100%;
}

/* ===== CARD base ===== */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 0;
  padding: var(--spacing-lg);
  transition: border-color var(--transition-fast), background var(--transition-fast);
}
.card:hover { border-color: var(--color-primary); background: var(--color-surface-hover); }
.card-title {
  font-family: var(--font-heading);
  font-size: 18px;
  color: var(--color-text);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: var(--spacing-sm);
}
.card-text { font-size: 14px; color: var(--color-text-secondary); line-height: 1.7; }

/* ===== TAG / LABEL ===== */
.tag {
  display: inline-block;
  padding: 4px 12px;
  font-family: var(--font-heading);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--color-primary);
  border: 1px solid var(--color-primary);
  background: transparent;
  line-height: 1.4;
}
.tag-accent {
  color: var(--color-accent);
  border-color: var(--color-accent);
}
.tag-highlight {
  color: var(--color-highlight);
  border-color: var(--color-highlight);
}