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

:root {
  --color-primary: #0066CC;
  --color-primary-hover: #0052A3;
  --color-primary-light: #E8F0FE;
  --color-secondary: #FF6600;
  --color-secondary-hover: #E55A00;
  --color-secondary-light: #FFF0E6;
  --color-bg: #F5F0E8;
  --color-card: #FFFFFF;
  --color-text: #1A1A1A;
  --color-text-secondary: #666666;
  --color-border: #E6E0D6;
  --color-border-strong: #CCC6BA;
  --color-success: #00B050;
  --color-error: #D32F2F;
  --gradient-primary: linear-gradient(135deg, #0066CC 0%, #004499 100%);
 --shadow-card: 0 4px 20px rgba(0,0,0,0.08);
  --shadow-hover: 0 8px 32px rgba(0,0,0,0.12);
  --font-heading: Inter Bold, 'Helvetica Neue', Arial, sans-serif;
  --font-body: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-digit: 'JetBrains Mono', 'SF Mono', monospace;
  --size-h1: 3rem;
  --size-h2: 2rem;
  --size-h3: 1.5rem;
  --size-body: 1rem;
  --size-small: 0.875rem;
  --line-height-body: 1.6;
  --line-height-heading: 1.2;
  --letter-spacing: 0.02em;
  --max-width: 1280px;
  --header-height: 64px;
  --transition: 0.25s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  --focus-outline: 3px solid #FF6600;
  --focus-offset: 4px;
}

[data-theme="dark"] {
  --color-bg: #1A1A2E;
  --color-card: #242438;
  --color-text: #F0F0F5;
  --color-text-secondary: #B0B0C0;
  --color-border: #3A3A50;
  --color-border-strong: #50506A;
  --color-primary-light: #1A2A4A;
  --color-secondary-light: #4A2A1A;
  --shadow-card: 0 4px 20px rgba(0,0,0,0.3);
  --shadow-hover: 0 8px 32px rgba(0,0,0,0.4);
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  font-size: var(--size-body);
  line-height: var(--line-height-body);
  color: var(--color-text);
  background-color: var(--color-bg);
  letter-spacing: var(--letter-spacing);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover {
  color: var(--color-secondary);
}

a:focus-visible,
button:focus-visible {
  outline: var(--focus-outline);
  outline-offset: var(--focus-offset);
}

ul {
  list-style: none;
}

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

::selection {
  background-color: var(--color-primary);
  color: #fff;
}

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--header-height);
  background: transparent;
  transition: background var(--transition), box-shadow var(--transition);
}

.site-header.scrolled {
  background: rgba(245, 240, 232, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 2px 24px rgba(0,0,0,0.06);
}

[data-theme="dark"] .site-header.scrolled {
  background: rgba(26, 26, 46, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
}

.logo {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  color: var(--color-primary);
  letter-spacing: 0.04em;
  flex-shrink: 0;
  text-decoration: none;
}

.logo:hover {
  color: var(--color-primary-hover);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 40px;
  height: 40px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  gap: 5px;
  border-radius: 4px;
  transition: background var(--transition);
}

.nav-toggle:hover {
  background: var(--color-primary-light);
}

.nav-toggle-line {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-line:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-line:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-line:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.nav {
  display: flex;
  align-items: center;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  font-family: var(--font-heading);
  font-size: var(--size-small);
  color: var(--color-text);
  text-decoration: none;
  border-radius: 6px;
  transition: color var(--transition), background var(--transition);
  position: relative;
  letter-spacing: 0.04em;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  transform: translateX(-50%) scaleX(0);
  width: calc(100% - 32px);
  height: 2px;
  background: var(--color-primary);
  border-radius: 2px;
  transition: transform var(--transition);
}

.nav-link:hover {
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.nav-link:hover::after {
  transform: translateX(-50%) scaleX(1);
}

.nav-link[aria-current="page"] {
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.nav-link[aria-current="page"]::after {
  transform: translateX(-50%) scaleX(1);
  background: var(--color-primary);
}

.nav-index {
  font-family: var(--font-digit);
  font-size: 0.7rem;
  color: var(--color-text-secondary);
  opacity: 0.6;
  letter-spacing: 0.02em;
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px 18px;
  font-family: var(--font-heading);
  font-size: var(--size-small);
  color: #fff;
  background: var(--gradient-primary);
  border: none;
  border-radius: 6px;
  cursor: pointer;
  letter-spacing: 0.04em;
  transition: transform var(--transition), box-shadow var(--transition);
  flex-shrink: 0;
  margin-left: 12px;
}

.theme-toggle:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(0, 102, 204, 0.3);
}

.theme-toggle:active {
  transform: translateY(0);
}

.skip-link {
  position: absolute;
  top: -100%;
  left: 16px;
  padding: 12px 20px;
  background: var(--color-primary);
  color: #fff;
  font-family: var(--font-body);
  font-size: var(--size-small);
  border-radius: 0 0 6px 6px;
  z-index: 1100;
  transition: top 0.2s;
  text-decoration: none;
}

.skip-link:focus {
  top: 0;
  outline: var(--focus-outline);
  outline-offset: 2px;
}

.scroll-progress {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: var(--gradient-primary);
  transition: width 0.1s linear;
  pointer-events: none;
}

.site-footer {
  background: var(--color-card);
  border-top: 3px solid var(--color-border);
  padding: 60px 24px 32px;
  margin-top: 0;
  position: relative;
}

.site-footer::before {
  content: '';
  position: absolute;
  top: -3px;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary), var(--color-primary));
  opacity: 0.3;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1.5fr;
  gap: 40px;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.footer-logo {
  font-family: var(--font-heading);
  font-size: 1.6rem;
  color: var(--color-primary);
  text-decoration: none;
  letter-spacing: 0.04em;
}

.footer-logo:hover {
  color: var(--color-primary-hover);
}

.footer-tagline {
  font-size: var(--size-body);
  color: var(--color-text-secondary);
  line-height: var(--line-height-body);
  max-width: 320px;
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding-top: 4px;
}

.footer-links-label,
.footer-contact-label {
  font-family: var(--font-heading);
  font-size: var(--size-small);
  color: var(--color-text);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  opacity: 0.7;
  margin-bottom: 4px;
}

.footer-link {
  font-size: var(--size-body);
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color var(--transition), padding-left var(--transition);
  padding-left: 0;
}

.footer-link:hover {
  color: var(--color-primary);
  padding-left: 4px;
}

.footer-contact {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-top: 4px;
}

.footer-contact-item {
  font-size: var(--size-small);
  color: var(--color-text-secondary);
  line-height: 1.5;
}

.footer-bottom {
  grid-column: 1 / -1;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 32px;
  margin-top: 16px;
  border-top: 1px solid var(--color-border);
  font-size: var(--size-small);
  color: var(--color-text-secondary);
}

.footer-copyright,
.footer-icp {
  font-size: var(--size-small);
  color: var(--color-text-secondary);
}

.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-card);
  color: var(--color-primary);
  font-size: 1.4rem;
  border: 2px solid var(--color-border);
  border-radius: 50%;
  box-shadow: var(--shadow-card);
  cursor: pointer;
  text-decoration: none;
  opacity: 0;
  transform: translateY(20px) scale(0.8);
  transition: opacity var(--transition), transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  pointer-events: none;
  z-index: 900;
}

.back-to-top.visible {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

.back-to-top:hover {
  border-color: var(--color-secondary);
  color: var(--color-secondary);
  box-shadow: var(--shadow-hover);
  transform: translateY(-3px) scale(1);
}

.back-to-top:focus-visible {
  outline: var(--focus-outline);
  outline-offset: var(--focus-offset);
}

.img-container {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;
  background: var(--color-border);
  border-radius: 8px;
  overflow: hidden;
}

.img-container-landscape {
  padding-bottom: 75%;
}

.img-container-portrait {
  padding-bottom: 133.33%;
}

.img-container > img,
.img-container-landscape > img,
.img-container-portrait > img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
  html {
    scroll-behavior: auto;
  }
}

@media (max-width: 1024px) {
  .footer-inner {
    grid-template-columns: 1fr 1fr;
    gap: 32px;
  }
  .footer-brand {
    grid-column: 1 / -1;
  }
}

@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }

  .nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--color-card);
    padding: 24px 32px;
    transform: translateX(100%);
    transition: transform var(--transition);
    overflow-y: auto;
    z-index: 999;
  }

  .nav[data-open] {
    transform: translateX(0);
  }

  .nav-list {
    flex-direction: column;
    gap: 4px;
    align-items: stretch;
  }

  .nav-link {
    padding: 14px 20px;
    font-size: 1.1rem;
    border-radius: 8px;
  }

  .nav-link::after {
    display: none;
  }

  .nav-link[aria-current="page"] {
    border-left: 4px solid var(--color-primary);
  }

  .nav-index {
    font-size: 0.8rem;
  }

  .theme-toggle {
    margin-left: 8px;
    padding: 6px 14px;
    font-size: 0.75rem;
  }

  .footer-inner {
    grid-template-columns: 1fr;
    gap: 28px;
  }

  .footer-bottom {
    flex-direction: column;
    gap: 8px;
    align-items: flex-start;
  }

  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 44px;
    height: 44px;
    font-size: 1.2rem;
  }
}

@media (max-width: 480px) {
  .header-inner {
    padding: 0 16px;
  }

  .logo {
    font-size: 1.2rem;
  }

  .theme-toggle {
    display: none;
  }

  .nav {
    padding: 16px 20px;
  }

  .site-footer {
    padding: 40px 16px 24px;
  }
}