/* ===== RESET ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; -moz-text-size-adjust: 100%; text-size-adjust: 100%; scroll-behavior: smooth; }
body { min-height: 100vh; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }
img, svg { display: block; max-width: 100%; }
ul, ol { list-style: none; }
a { text-decoration: none; color: inherit; }
button { font: inherit; color: inherit; border: none; background: none; cursor: pointer; }
:focus-visible { outline: 2px solid #0055FF; outline-offset: 2px; border-radius: 2px; }
@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; } }

/* ===== CSS VARIABLES ===== */
:root {
  --color-primary: #0055FF;
  --color-primary-dark: #0033AA;
  --color-accent: #FF6B35;
  --color-accent-light: #FF9A5E;
  --color-bg: #FFFFFF;
  --color-bg-dark: #1A1A1A;
  --color-bg-mid: #2A2A2A;
  --color-text: #1A1A1A;
  --color-text-secondary: #666666;
  --color-text-on-primary: #FFFFFF;
  --color-text-on-accent: #FFFFFF;
  --color-text-on-dark: #EEEEEE;
  --color-border: #E0E0E0;
  --color-border-light: #F0F0F0;

  --font-heading: 'Inter', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-nav: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;

  --fs-h1: clamp(2rem, 5vw, 3.5rem);
  --fs-h2: clamp(1.5rem, 3.5vw, 2.5rem);
  --fs-h3: clamp(1.25rem, 2.5vw, 1.75rem);
  --fs-body: 1rem;
  --fs-small: 0.875rem;
  --fs-tiny: 0.75rem;

  --lh-heading: 1.15;
  --lh-body: 1.6;

  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 5rem;

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 16px;

  --header-height: 64px;
  --max-width: 1200px;

  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===== TYPOGRAPHY ===== */
body { font-family: var(--font-body); font-size: var(--fs-body); line-height: var(--lh-body); color: var(--color-text); background: var(--color-bg); }
h1, h2, h3, h4, h5, h6 { font-family: var(--font-heading); font-weight: 700; font-style: italic; line-height: var(--lh-heading); color: var(--color-text); }
h1 { font-size: var(--fs-h1); }
h2 { font-size: var(--fs-h2); }
h3 { font-size: var(--fs-h3); }
p { margin-bottom: var(--space-md); }
small { font-size: var(--fs-small); color: var(--color-text-secondary); }
a { color: var(--color-primary); transition: color var(--transition-fast); }
a:hover { color: var(--color-primary-dark); }
::selection { background: var(--color-primary); color: var(--color-text-on-primary); }

/* ===== SKIP LINK ===== */
.skip-link {
  position: absolute; top: -100%; left: var(--space-md); z-index: 10000;
  padding: var(--space-sm) var(--space-md); background: var(--color-bg-dark); color: var(--color-text-on-dark);
  font-family: var(--font-nav); font-size: var(--fs-small); font-weight: 600; border-radius: var(--radius-sm);
  transition: top var(--transition-fast);
}
.skip-link:focus { top: var(--space-sm); color: var(--color-text-on-dark); }
.skip-link:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; }

/* ===== SCROLL PROGRESS ===== */
.scroll-progress {
  position: absolute; top: 0; left: 0; width: 0%; height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  z-index: 9999; transition: width 0.1s linear;
  will-change: width;
}
@media (prefers-reduced-motion: reduce) { .scroll-progress { display: none; } }

/* ===== HEADER ===== */
.site-header {
  position: sticky; top: 0; z-index: 1000;
  background: var(--color-bg-dark); color: var(--color-text-on-dark);
  border-bottom: 2px solid var(--color-primary);
  min-height: var(--header-height);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  max-width: var(--max-width); margin: 0 auto; padding: 0 var(--space-lg);
  height: var(--header-height); position: relative;
}
.header-logo { display: flex; align-items: center; gap: var(--space-sm); flex-shrink: 0; }
.logo-symbol { display: flex; align-items: center; line-height: 0; }
.logo-text { font-family: var(--font-heading); font-size: 1.25rem; font-weight: 700; font-style: italic; color: var(--color-text-on-dark); letter-spacing: 0.02em; }
.header-nav { display: flex; align-items: center; }
.nav-list { display: flex; align-items: center; gap: var(--space-xs); }
.nav-item { position: relative; }
.nav-link {
  display: inline-block; padding: var(--space-sm) var(--space-md);
  font-family: var(--font-nav); font-size: 0.875rem; font-weight: 600;
  letter-spacing: 0.5px; color: var(--color-text-on-dark);
  position: relative; transition: color var(--transition-fast);
}
.nav-link::after {
  content: ''; position: absolute; bottom: 2px; left: var(--space-md);
  width: 0; height: 2px; background: var(--color-primary);
  transition: width var(--transition-smooth);
}
.nav-link:hover { color: var(--color-primary); }
.nav-link:hover::after { width: calc(100% - var(--space-md) * 2); }
.nav-link[aria-current="page"] { color: var(--color-primary); }
.nav-link[aria-current="page"]::after { width: calc(100% - var(--space-md) * 2); background: var(--color-primary); }
.nav-link:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 4px; border-radius: var(--radius-sm); }

/* ===== BUTTON ===== */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: var(--space-sm) var(--space-lg); border-radius: var(--radius-sm);
  font-family: var(--font-nav); font-size: 0.875rem; font-weight: 600;
  letter-spacing: 0.5px; cursor: pointer; transition: all var(--transition-fast);
  border: 2px solid transparent; text-align: center;
}
.btn-primary {
  background: var(--color-accent); color: var(--color-text-on-accent); border-color: var(--color-accent);
  position: relative; overflow: hidden;
}
.btn-primary::before {
  content: ''; position: absolute; inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.2) 0%, transparent 60%);
  opacity: 0; transition: opacity var(--transition-smooth);
}
.btn-primary:hover { background: var(--color-accent-light); border-color: var(--color-accent-light); color: var(--color-text-on-accent); }
.btn-primary:hover::before { opacity: 1; }
.btn-primary:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; }

/* ===== NAV TOGGLE (MOBILE) ===== */
.nav-toggle {
  display: none; flex-direction: column; justify-content: center; align-items: center;
  width: 40px; height: 40px; padding: 8px; border-radius: var(--radius-sm);
  background: transparent; transition: background var(--transition-fast);
}
.nav-toggle:hover { background: rgba(255,255,255,0.1); }
.nav-toggle:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; }
.toggle-bar { display: block; width: 24px; height: 2px; background: var(--color-text-on-dark); margin: 3px 0; transition: all var(--transition-smooth); transform-origin: center; }
[data-nav-toggle][aria-expanded="true"] .toggle-bar:nth-child(1) { transform: translateY(5px) rotate(45deg); }
[data-nav-toggle][aria-expanded="true"] .toggle-bar:nth-child(2) { opacity: 0; }
[data-nav-toggle][aria-expanded="true"] .toggle-bar:nth-child(3) { transform: translateY(-5px) rotate(-45deg); }

/* ===== MOBILE NAV ===== */
@media (max-width: 768px) {
  .nav-toggle { display: flex; }
  .header-nav {
    position: absolute; top: var(--header-height); left: 0; right: 0;
    background: var(--color-bg-dark); border-bottom: 2px solid var(--color-primary);
    max-height: 0; overflow: hidden; transition: max-height var(--transition-smooth);
    box-shadow: 0 8px 24px rgba(0,0,0,0.3);
  }
  .header-nav[data-open] { max-height: 500px; }
  .nav-list { flex-direction: column; gap: 0; padding: var(--space-md) 0; }
  .nav-item { width: 100%; }
  .nav-link { display: block; padding: var(--space-md) var(--space-lg); font-size: 1rem; border-left: 3px solid transparent; }
  .nav-link::after { display: none; }
  .nav-link:hover { background: rgba(0,85,255,0.1); border-left-color: var(--color-primary); }
  .nav-link[aria-current="page"] { background: rgba(0,85,255,0.15); border-left-color: var(--color-primary); color: var(--color-primary); }
  .header-cta { display: none; }
  .header-inner { padding: 0 var(--space-md); }
}

/* ===== FOOTER ===== */
.site-footer {
  background: var(--color-bg-dark); color: var(--color-text-on-dark);
  border-top: 3px solid var(--color-primary); position: relative;
}
.site-footer::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0; height: 1px;
  background: linear-gradient(90deg, transparent, var(--color-primary), var(--color-accent), transparent);
}
.footer-inner {
  max-width: var(--max-width); margin: 0 auto; padding: var(--space-xl) var(--space-lg) var(--space-lg);
  display: grid; grid-template-columns: 1fr 1fr 1fr; gap: var(--space-lg);
}
.footer-brand { display: flex; flex-direction: column; gap: var(--space-sm); }
.footer-logo { font-family: var(--font-heading); font-size: 1.5rem; font-weight: 700; font-style: italic; color: var(--color-text-on-dark); letter-spacing: 0.02em; }
.footer-tagline { font-size: var(--fs-small); color: var(--color-accent); font-weight: 500; letter-spacing: 0.3px; }
.footer-contact { display: flex; flex-direction: column; gap: var(--space-sm); }
.contact-item { font-size: var(--fs-small); color: var(--color-text-on-dark); margin-bottom: 0; }
.contact-item::before { content: '›'; color: var(--color-primary); font-weight: 700; margin-right: var(--space-sm); }
.footer-links { display: flex; flex-direction: column; gap: var(--space-sm); align-items: flex-end; }
.footer-link { font-size: var(--fs-small); color: var(--color-text-on-dark); font-weight: 500; transition: color var(--transition-fast); position: relative; padding-bottom: 2px; }
.footer-link::after { content: ''; position: absolute; bottom: 0; left: 0; width: 0; height: 1px; background: var(--color-primary); transition: width var(--transition-smooth); }
.footer-link:hover { color: var(--color-primary); }
.footer-link:hover::after { width: 100%; }
.footer-link:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; border-radius: var(--radius-sm); }
.footer-divider { grid-column: 1 / -1; height: 1px; background: var(--color-border); opacity: 0.15; margin: var(--space-sm) 0; }
.footer-bottom { grid-column: 1 / -1; display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: var(--space-md); padding-top: var(--space-md); }
.copyright, .icp { font-size: var(--fs-tiny); color: var(--color-text-secondary); margin-bottom: 0; }
.trust-note { font-size: var(--fs-tiny); color: var(--color-text-secondary); width: 100%; text-align: center; margin-top: var(--space-sm); opacity: 0.7; }

/* ===== FOOTER RESPONSIVE ===== */
@media (max-width: 768px) {
  .footer-inner { grid-template-columns: 1fr; gap: var(--space-lg); padding: var(--space-lg) var(--space-md); }
  .footer-links { align-items: flex-start; }
  .footer-bottom { flex-direction: column; align-items: flex-start; gap: var(--space-sm); }
}

/* ===== CONTAINER ===== */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 var(--space-lg); }
@media (max-width: 768px) { .container { padding: 0 var(--space-md); } }

/* ===== SECTION ===== */
.section { padding: var(--space-2xl) 0; position: relative; }
.section-number { font-family: var(--font-heading); font-size: var(--fs-h3); font-weight: 700; color: var(--color-primary); font-style: italic; margin-bottom: var(--space-sm); }
.section-title { margin-bottom: var(--space-lg); }
.section-subtitle { font-size: var(--fs-small); color: var(--color-text-secondary); font-weight: 400; font-style: normal; margin-top: var(--space-xs); }

/* ===== BREADCRUMB ===== */
.breadcrumb { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-sm); padding: var(--space-md) 0; font-size: var(--fs-small); color: var(--color-text-secondary); }
.breadcrumb-item { display: flex; align-items: center; gap: var(--space-sm); }
.breadcrumb-item + .breadcrumb-item::before { content: '/'; color: var(--color-border); font-weight: 300; }
.breadcrumb-link { color: var(--color-text-secondary); transition: color var(--transition-fast); }
.breadcrumb-link:hover { color: var(--color-primary); }
.breadcrumb-link[aria-current="page"] { color: var(--color-text); font-weight: 600; }

/* ===== GRID ===== */
.grid { display: grid; gap: var(--space-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: 768px) { .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; } }
@media (min-width: 769px) and (max-width: 1024px) { .grid-4 { grid-template-columns: 1fr 1fr; } }

/* ===== UTILITY ===== */
.text-center { text-align: center; }
.text-primary { color: var(--color-primary); }
.text-accent { color: var(--color-accent); }
.bg-dark { background: var(--color-bg-dark); color: var(--color-text-on-dark); }
.bg-primary { background: var(--color-primary); color: var(--color-text-on-primary); }
.bg-accent { background: var(--color-accent); color: var(--color-text-on-accent); }
.mt-lg { margin-top: var(--space-lg); }
.mb-lg { margin-bottom: var(--space-lg); }
.p-lg { padding: var(--space-lg); }

/* ===== RESPONSIVE BREAKPOINTS ===== */
@media (max-width: 480px) {
  :root { --space-lg: 1.25rem; --space-xl: 2rem; --space-2xl: 3rem; }
  .header-inner { padding: 0 var(--space-md); }
}
@media (min-width: 769px) and (max-width: 1024px) {
  .nav-link { padding: var(--space-sm) var(--space-sm); font-size: 0.8125rem; }
}

/* ===== DECORATIVE ELEMENTS ===== */
.speed-line { height: 2px; background: linear-gradient(90deg, var(--color-primary), transparent); margin: var(--space-lg) 0; }
.diagonal-bg { position: relative; overflow: hidden; }
.diagonal-bg::before { content: ''; position: absolute; top: -20%; right: -10%; width: 40%; height: 140%; background: linear-gradient(135deg, transparent 40%, rgba(0,85,255,0.05) 60%, transparent 80%); transform: rotate(12deg); pointer-events: none; }

/* ===== IMAGE CONTAINER ===== */
.img-wrap { position: relative; overflow: hidden; background: var(--color-border-light); }
.img-wrap img { width: 100%; height: 100%; object-fit: cover; transition: transform var(--transition-smooth); }
.img-wrap:hover img { transform: scale(1.03); }
.img-ratio-16-9 { aspect-ratio: 16 / 9; }
.img-ratio-4-3 { aspect-ratio: 4 / 3; }
.img-ratio-1-1 { aspect-ratio: 1 / 1; }

/* ===== CARD ===== */
.card { background: var(--color-bg); border: 1px solid var(--color-border); border-radius: var(--radius-md); padding: var(--space-lg); transition: border-color var(--transition-fast), box-shadow var(--transition-fast); }
.card:hover { border-color: var(--color-primary); box-shadow: 0 4px 20px rgba(0,85,255,0.08); }
.card-title { font-size: var(--fs-h3); font-weight: 700; font-style: italic; margin-bottom: var(--space-sm); }
.card-text { font-size: var(--fs-small); color: var(--color-text-secondary); }