/* ===== CSS Variables ===== */
:root {
  --primary: #1890ff;
  --primary-dark: #096dd9;
  --primary-light: #e6f7ff;
  --text-dark: #333;
  --text-gray: #666;
  --text-light: #999;
  --bg-white: #fff;
  --bg-gray: #f5f5f5;
  --bg-dark: #2b2b2b;
  --footer-bg: #333;
  --border: #e8e8e8;
  --container: 1200px;
  --header-h: 70px;
  --transition: 0.3s cubic-bezier(0.22, 1, 0.36, 1);
  --shadow-primary: 0 8px 24px rgba(24, 144, 255, 0.28);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: "Microsoft YaHei", "PingFang SC", "Helvetica Neue", Arial, sans-serif;
  color: var(--text-dark);
  line-height: 1.6;
  background: var(--bg-white);
  overflow-x: hidden;
}

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

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

ul { list-style: none; }

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 20px;
}

/* ===== Header ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--bg-white);
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
  height: var(--header-h);
}

.header-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 20px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.lang-switch {
  display: flex;
  align-items: center;
  background: var(--bg-gray);
  border-radius: 20px;
  padding: 3px;
  border: 1px solid var(--border);
  /* 视口宽度超出内容容器（1200px）时，语言开关向右悬浮到视口右缘（约 20px），
     忽略容器居中留白与内边距；宽度不足时保持原位 */
  transform: translateX(max(0px, calc((100vw - 1200px) / 2)));
}

.lang-switch button {
  border: none;
  background: transparent;
  color: var(--text-gray);
  font-size: 12px;
  font-weight: 600;
  padding: 5px 12px;
  border-radius: 16px;
  cursor: pointer;
  transition: background 0.25s ease, color 0.25s ease, box-shadow 0.25s ease;
  line-height: 1.2;
}

.lang-switch button.active {
  background: var(--bg-white);
  color: #00A2E9;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.lang-switch button:not(.active):hover {
  color: #00A2E9;
}

.logo img {
  height: 40px;
  width: auto;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 40px;
  margin-left: auto;
}

.main-nav a {
  font-size: 15px;
  font-weight: 700;
  color: var(--text-dark);
  padding: 8px 0;
  position: relative;
  white-space: nowrap;
}

.main-nav a:hover,
.main-nav a.active {
  color: #00A2E9;
}

.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-dark);
  transition: var(--transition);
}

.menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ===== Page Banner ===== */
.page-banner {
  position: relative;
  margin-top: var(--header-h);
  height: 400px;
  background-size: cover;
  background-position: center;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: #fff;
}

.page-banner::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.35);
}

.page-banner .banner-content {
  position: relative;
  z-index: 1;
}

.page-banner h2 {
  font-size: 36px;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: 2px;
}

.page-banner p {
  font-size: 18px;
  opacity: 0.9;
}

.page-banner .page-title {
  font-size: 24px;
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid rgba(255,255,255,0.5);
  display: inline-block;
}

/* ===== Breadcrumb ===== */
.breadcrumb {
  background: var(--bg-gray);
  padding: 12px 0;
  font-size: 14px;
  color: var(--text-gray);
}

.breadcrumb .container {
  display: flex;
  align-items: center;
  gap: 8px;
}

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

/* ===== Section Title ===== */
.section-title {
  text-align: center;
  margin-bottom: 50px;
}

.section-title h2 {
  font-size: 32px;
  color: var(--text-dark);
  font-weight: 600;
  position: relative;
  display: inline-block;
}

.section-title h2 span {
  color: var(--primary);
}

.section-title h2 span.plain {
  color: var(--text-dark);
}

.section-title .subtitle {
  font-size: 14px;
  color: var(--text-light);
  margin-top: 8px;
  letter-spacing: 3px;
  text-transform: uppercase;
}

.section-title .watermark {
  font-size: 60px;
  color: rgba(0,0,0,0.04);
  font-weight: 700;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  white-space: nowrap;
  pointer-events: none;
  z-index: 0;
}

.section-title .title-wrap {
  position: relative;
  z-index: 1;
}

/* ===== Footer ===== */
.site-footer {
  background: var(--footer-bg);
  color: #ccc;
  padding: 40px 0 20px;
}

.footer-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 30px;
  border-bottom: 1px solid rgba(255,255,255,0.1);
  margin-bottom: 30px;
}

.footer-logo img {
  height: 36px;
  filter: brightness(0) invert(1);
}

.footer-nav {
  display: flex;
  gap: 30px;
}

.footer-nav a {
  color: #ccc;
  font-size: 14px;
}

.footer-nav a:hover { color: #fff; }

.footer-contact {
  display: flex;
  flex-wrap: wrap;
  gap: 30px;
  margin-bottom: 30px;
  font-size: 13px;
}

.footer-contact-item {
  display: flex;
  align-items: center;
  gap: 8px;
}

.footer-contact-item img {
  width: 21px;
  height: 21px;
  filter: brightness(0) invert(0.7);
  flex-shrink: 0;
}

.footer-bottom {
  text-align: center;
  font-size: 12px;
  color: #888;
  padding-top: 20px;
  border-top: 1px solid rgba(255,255,255,0.08);
}

.footer-bottom a:hover {
  color: #fff;
  text-decoration: underline;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 11px 30px;
  border-radius: 6px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: transform 0.25s ease, box-shadow 0.25s ease, background 0.25s ease, color 0.25s ease, border-color 0.25s ease;
  border: none;
  letter-spacing: 0.3px;
}

.btn:active {
  transform: translateY(0) scale(0.98);
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, #36a3ff 100%);
  color: #fff;
  box-shadow: 0 4px 14px rgba(24, 144, 255, 0.25);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-primary);
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 100%);
}

.btn-outline {
  border: 1.5px solid var(--primary);
  color: var(--primary);
  background: transparent;
}

.btn-outline:hover {
  background: var(--primary-light);
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(24, 144, 255, 0.15);
}

/* ===== Responsive ===== */
@media (max-width: 992px) {
  .main-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    background: var(--bg-white);
    flex-direction: column;
    padding: 20px;
    gap: 0;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    transform: translateY(-120%);
    opacity: 0;
    transition: var(--transition);
    pointer-events: none;
  }

  .main-nav.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .main-nav a {
    width: 100%;
    padding: 14px 0;
    border-bottom: 1px solid var(--border);
    text-align: center;
  }

  .menu-toggle { display: flex; }

  .header-actions { margin-left: auto; }

  .page-banner { height: 280px; }
  .page-banner h2 { font-size: 26px; }

  .footer-top {
    flex-direction: column;
    gap: 20px;
    text-align: center;
  }

  .footer-nav { flex-wrap: wrap; justify-content: center; }

  .footer-contact {
    flex-direction: column;
    gap: 12px;
  }
}

@media (max-width: 576px) {
  html { font-size: 14px; }

  .page-banner { height: 220px; }
  .page-banner h2 { font-size: 22px; }
  .page-banner p { font-size: 14px; }

  .section-title h2 { font-size: 24px; }
  .section-title .watermark { font-size: 36px; }
}