:root {
  --header-offset: 122px;
  --primary: #26A9E0;
  --primary-dark: #1e8fbf;
  --accent: #EA7C07;
  --white: #FFFFFF;
  --dark: #000000;
  --bg-light: #F5F7FA;
}
body {
  margin: 0;
  padding-top: var(--header-offset);
  font-family: Arial, Helvetica, sans-serif;
  background: var(--white);
  color: #333333;
}
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: var(--white);
  box-shadow: 0 2px 15px rgba(0,0,0,0.1);
}
.header-top {
  background: linear-gradient(135deg, #1e8fbf 0%, #26A9E0 50%, #3bb5e8 100%);
  width: 100%;
}
.header-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 30px;
  min-height: 48px;
}
.logo {
  display: inline-block;
  font-size: 2.2rem;
  font-weight: 900;
  color: var(--white);
  text-decoration: none;
  letter-spacing: 2px;
  text-transform: uppercase;
  text-shadow: 0 2px 8px rgba(0,0,0,0.25);
  line-height: 1.2;
}
.logo:hover {
  color: #ffd700;
}
.desktop-nav-buttons {
  display: flex;
  gap: 10px;
  align-items: center;
}
.btn {
  display: inline-block;
  padding: 10px 20px;
  border-radius: 8px;
  font-weight: 700;
  font-size: 0.9rem;
  text-decoration: none;
  text-align: center;
  transition: transform 0.2s, box-shadow 0.2s;
  line-height: 1.2;
}
.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}
.btn-login {
  background: var(--accent);
  color: var(--white);
}
.btn-register {
  background: var(--primary);
  color: var(--white);
}
.btn-download {
  background: var(--dark);
  color: var(--white);
}
.main-nav {
  background: var(--white);
  width: 100%;
  display: flex;
  border-bottom: 1px solid #e0e0e0;
}
.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  padding: 0 20px;
  flex-wrap: wrap;
  gap: 4px;
}
.nav-link {
  display: inline-block;
  padding: 12px 14px;
  color: #333333;
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
  border-bottom: 3px solid transparent;
  transition: color 0.2s, border-color 0.2s;
}
.nav-link:hover {
  color: var(--primary);
  border-bottom-color: var(--primary);
}
.hamburger-menu {
  display: none;
  position: absolute;
  left: 15px;
  top: 12px;
  z-index: 1002;
  flex-direction: column;
  justify-content: space-between;
  width: 30px;
  height: 22px;
  cursor: pointer;
  padding: 0;
  background: transparent;
  border: none;
}
.hamburger-menu span {
  width: 100%;
  height: 3px;
  background: var(--white);
  border-radius: 2px;
  transition: all 0.3s ease;
}
.hamburger-menu.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}
.hamburger-menu.active span:nth-child(2) {
  opacity: 0;
}
.hamburger-menu.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}
.mobile-menu-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.5);
  z-index: 999;
  opacity: 0;
  transition: opacity 0.3s ease;
}
.mobile-menu-overlay.active {
  opacity: 1;
}
.mobile-nav-buttons {
  display: none;
}
.site-footer {
  background: #1a1a2e;
  color: var(--white);
  padding: 40px 20px 10px;
}
.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}
.footer-column h3 {
  color: var(--primary);
  font-size: 1.8rem;
  margin-bottom: 10px;
}
.footer-column h4 {
  color: var(--primary);
  font-size: 1.1rem;
  margin-bottom: 15px;
  border-bottom: 2px solid var(--primary);
  padding-bottom: 6px;
}
.footer-column p {
  font-size: 0.9rem;
  line-height: 1.6;
  color: #ccc;
}
.footer-nav {
  list-style: none;
  padding: 0;
  margin: 0;
}
.footer-nav li {
  margin-bottom: 8px;
}
.footer-nav a {
  color: #ddd;
  text-decoration: none;
  font-size: 0.9rem;
  transition: color 0.2s;
}
.footer-nav a:hover {
  color: var(--primary);
}
.footer-bottom {
  border-top: 1px solid #333;
  margin-top: 30px;
  padding-top: 15px;
  text-align: center;
  color: #aaa;
  font-size: 0.85rem;
}
@media (max-width: 768px) {
  :root {
    --header-offset: 110px;
  }
  .header-container {
    width: 100%;
    max-width: none;
    padding: 10px 15px;
    justify-content: center;
    position: relative;
    min-height: 50px;
  }
  .logo {
    font-size: 1.8rem;
    text-align: center;
  }
  .desktop-nav-buttons {
    display: none;
  }
  .hamburger-menu {
    display: flex;
  }
  .mobile-nav-buttons {
    display: flex;
    justify-content: center;
    gap: 8px;
    background: var(--primary-dark);
    padding: 8px 10px;
    width: 100%;
  }
  .mobile-nav-buttons .btn {
    flex: 1;
    padding: 8px 12px;
    font-size: 0.8rem;
  }
  .main-nav {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 70%;
    max-width: 300px;
    height: 100%;
    background: var(--white);
    box-shadow: 4px 0 20px rgba(0,0,0,0.2);
    flex-direction: column;
    align-items: stretch;
    padding-top: 70px;
    transform: translateX(-100%);
    transition: transform 0.3s ease;
    z-index: 1001;
  }
  .main-nav.active {
    display: flex;
    transform: translateX(0);
  }
  .nav-container {
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 0;
    padding: 0;
    width: 100%;
    max-width: none;
  }
  .nav-link {
    padding: 14px 20px;
    border-bottom: 1px solid #f0f0f0;
    font-size: 1rem;
    text-align: left;
  }
  .nav-link:hover {
    background: #f5f5f5;
    border-bottom: 1px solid #f0f0f0;
    color: var(--primary);
  }
  .mobile-menu-overlay.active {
    display: block;
  }
  .footer-container {
    grid-template-columns: 1fr;
    gap: 20px;
  }
  .page-content img {
    max-width: 100% !important;
    height: auto !important;
    display: block;
  }
  .page-content {
    overflow-x: hidden;
    max-width: 100%;
  }
  body {
    overflow-x: hidden;
  }
}
/* 移动端内容区防溢出（系统追加，请勿删除） */
@media (max-width: 768px) {
  .page-content img {
    max-width: 100% !important;
    height: auto !important;
    display: block;
  }
  .page-content {
    overflow-x: hidden;
    max-width: 100%;
  }
  body {
    overflow-x: hidden;
  }
}
/* 内容保护（系统追加，请勿删除） */
body {
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}
input, textarea, select, [contenteditable="true"] {
  -webkit-user-select: text;
  -moz-user-select: text;
  user-select: text;
}