/* Reset & base */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}
body {
  font-family: 'Source Han Serif SC', 'Noto Serif SC', serif;
  font-size: 1rem;
  line-height: 1.6;
  color: #0B1A2E;
  background-color: #F5F5F0;
}
img, svg {
  max-width: 100%;
  height: auto;
  display: block;
}
a {
  color: inherit;
  text-decoration: none;
}
ul {
  list-style: none;
}
:focus-visible {
  outline: 2px solid #39FF14;
  outline-offset: 2px;
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
  html {
    scroll-behavior: auto;
  }
}

/* CSS Variables */
:root {
  --color-primary-dark-blue: #0B1A2E;
  --color-primary-gold: #D4A843;
  --color-accent-fluorescent-green: #39FF14;
  --color-background-light: #F5F5F0;
  --color-background-dark-section: #111820;
  --color-text-primary-light: #FFFFFF;
  --color-text-primary-dark: #0B1A2E;
  --color-text-secondary: #6E7B8B;
  --color-border-subtle: #2C3E50;
  --color-highlight-amber: #FFB347;
  --font-heading: 'Noto Sans SC', sans-serif;
  --font-body: 'Source Han Serif SC', 'Noto Serif SC', serif;
  --font-mono: 'JetBrains Mono', monospace;
  --container-max-width: 1280px;
  --header-height: 80px;
}

/* Container */
.container {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}
@media (min-width: 768px) {
  .container {
    padding-left: 2rem;
    padding-right: 2rem;
  }
}

/* Skip link */
.skip-link {
  position: absolute;
  top: -100%;
  left: 0;
  z-index: 1000;
  padding: 0.5rem 1rem;
  background: var(--color-primary-gold);
  color: var(--color-primary-dark-blue);
  font-family: var(--font-heading);
  font-weight: bold;
  text-decoration: none;
  transition: top 0.2s;
}
.skip-link:focus {
  top: 0;
  outline: none;
}

/* Header */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 900;
  background: var(--color-primary-dark-blue);
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}
.brand-layer {
  background: #0A1627;
  border-bottom: 1px solid var(--color-border-subtle);
}
.brand-layer-inner {
  display: flex;
  align-items: center;
  height: 44px;
  gap: 1rem;
}
.logo {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}
.brand-tagline {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  white-space: nowrap;
}
.nav-layer {
  height: 36px;
}
.nav-layer-inner {
  display: flex;
  align-items: center;
  height: 100%;
  position: relative;
}
.nav {
  display: flex;
  flex: 1;
}
.nav-list {
  display: flex;
  gap: 0.25rem;
}
.nav-list a {
  display: flex;
  align-items: center;
  height: 36px;
  padding: 0 0.8rem;
  font-family: var(--font-heading);
  font-size: 0.9rem;
  color: var(--color-text-primary-light);
  transition: background 0.2s, color 0.2s;
  border-radius: 2px;
}
.nav-list a:hover,
.nav-list a:focus-visible {
  background: rgba(212,168,67,0.2);
  color: var(--color-primary-gold);
}
.nav-list a[aria-current="page"] {
  color: var(--color-primary-gold);
  border-bottom: 2px solid var(--color-primary-gold);
}
.nav-toggle {
  display: none;
  background: none;
  border: none;
  padding: 0.5rem;
  cursor: pointer;
  color: var(--color-text-primary-light);
}
.nav-toggle-icon,
.nav-toggle-icon::before,
.nav-toggle-icon::after {
  display: block;
  width: 24px;
  height: 2px;
  background: currentColor;
  transition: all 0.3s;
}
.nav-toggle-icon {
  position: relative;
}
.nav-toggle-icon::before,
.nav-toggle-icon::after {
  content: '';
  position: absolute;
  left: 0;
}
.nav-toggle-icon::before {
  top: -7px;
}
.nav-toggle-icon::after {
  top: 7px;
}
.nav-toggle[aria-expanded="true"] .nav-toggle-icon {
  background: transparent;
}
.nav-toggle[aria-expanded="true"] .nav-toggle-icon::before {
  top: 0;
  transform: rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-icon::after {
  top: 0;
  transform: rotate(-45deg);
}
@media (max-width: 767px) {
  .site-header {
    position: relative; /* 固定顶部会遮挡内容，改为相对 */
  }
  .brand-layer-inner {
    height: 48px;
  }
  .nav-layer {
    height: auto;
  }
  .nav-toggle {
    display: block;
  }
  .nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: var(--color-background-dark-section);
    flex-direction: column;
    padding: 0.5rem 0;
    box-shadow: 0 4px 8px rgba(0,0,0,0.4);
  }
  .nav[data-open] {
    display: flex;
  }
  .nav-list {
    flex-direction: column;
    gap: 0;
  }
  .nav-list a {
    height: 44px;
    padding: 0 1rem;
    border-bottom: 1px solid var(--color-border-subtle);
  }
  .nav-list a:last-child {
    border-bottom: none;
  }
  .nav-list a[aria-current="page"] {
    border-bottom: 1px solid var(--color-primary-gold);
  }
}

/* Footer */
.site-footer {
  background: var(--color-primary-dark-blue);
  color: var(--color-text-primary-light);
  padding: 2.5rem 0;
  font-size: 0.9rem;
}
.footer-inner {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}
@media (min-width: 768px) {
  .footer-inner {
    grid-template-columns: 1fr 1fr 1fr;
  }
}
.footer-logo {
  display: inline-block;
  margin-bottom: 0.5rem;
}
.footer-tagline {
  color: var(--color-text-secondary);
  font-family: var(--font-mono);
  font-size: 0.8rem;
}
.footer-nav-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.footer-nav-list a {
  color: var(--color-primary-gold);
  transition: color 0.2s;
}
.footer-nav-list a:hover,
.footer-nav-list a:focus-visible {
  color: var(--color-accent-fluorescent-green);
}
.footer-contact p {
  margin-bottom: 0.3rem;
}
.footer-contact a {
  color: var(--color-primary-gold);
}
.footer-legal {
  grid-column: 1 / -1;
  text-align: center;
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-border-subtle);
  font-size: 0.8rem;
  color: var(--color-text-secondary);
}

/* Scroll progress bar */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: rgba(255,255,255,0.1);
  z-index: 999;
  pointer-events: none;
}
.scroll-progress-inner {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary-gold), var(--color-accent-fluorescent-green));
  width: 0%;
  transition: width 0.1s linear;
}
@media (prefers-reduced-motion: reduce) {
  .scroll-progress-inner {
    transition: none;
  }
}

/* General button */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.6rem 1.5rem;
  font-family: var(--font-heading);
  font-weight: bold;
  font-size: 0.95rem;
  border: 2px solid var(--color-primary-gold);
  border-radius: 2px;
  background: transparent;
  color: var(--color-primary-gold);
  cursor: pointer;
  transition: background 0.2s, color 0.2s, border-color 0.2s;
  text-decoration: none;
}
.btn:hover,
.btn:focus-visible {
  background: var(--color-primary-gold);
  color: var(--color-primary-dark-blue);
  border-color: var(--color-primary-gold);
}

/* Breadcrumb */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-bottom: 1rem;
}
.breadcrumb a {
  color: var(--color-primary-gold);
}
.breadcrumb a:hover {
  text-decoration: underline;
}
.breadcrumb .divider {
  color: var(--color-text-secondary);
}

/* Card (for future pages) */
.card {
  background: var(--color-background-light);
  border: 1px solid var(--color-border-subtle);
  border-radius: 2px;
  padding: 1.5rem;
  box-shadow: 0 2px 4px rgba(0,0,0,0.02);
}
.card:hover {
  box-shadow: 0 4px 12px rgba(0,0,0,0.06);
}

/* Image placeholder base */
.image-placeholder {
  background: var(--color-border-subtle);
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

/* Main content offset for fixed header */
#main-content {
  padding-top: calc(var(--header-height) + 0px); /* 后续页面根据header高度调整 */
}
@media (max-width: 767px) {
  #main-content {
    padding-top: 0;
  }
}