:root{--header-offset:120px;--header-top-bg:#0d1b2a;--nav-bg:#ffffff;--primary:#26A9E0;--accent:#EA7C07;--text-dark:#0d1b2a;--text-light:#ffffff;}
body{padding-top:var(--header-offset);margin:0;background:#FFFFFF;font-family:'Segoe UI',Roboto,sans-serif;}
.site-header{position:fixed;top:0;left:0;width:100%;min-height:auto;background:var(--nav-bg);box-shadow:0 4px 12px rgba(0,0,0,0.15);z-index:1000;}
.header-top{background:var(--header-top-bg);width:100%;}
.header-container{max-width:1200px;margin:0 auto;display:flex;justify-content:space-between;align-items:center;padding:10px 20px;}
.logo{color:var(--text-light);font-size:1.4rem;font-weight:800;text-decoration:none;text-transform:uppercase;letter-spacing:0.5px;display:inline-block;}
.logo:hover{color:var(--primary);}
.desktop-nav-buttons{display:flex;gap:12px;align-items:center;}
.btn{text-decoration:none;display:inline-block;padding:10px 24px;border-radius:40px;font-weight:700;font-size:0.9rem;border:none;cursor:pointer;color:#FFFFFF;background:var(--primary);transition:all 0.3s ease;}
.btn:hover{opacity:0.9;transform:translateY(-2px);box-shadow:0 6px 12px rgba(0,0,0,0.2);}
.btn-register{background:linear-gradient(135deg,#EA7C07,#f7b733);}
.btn-login{background:linear-gradient(135deg,#26A9E0,#2b5876);}
.main-nav{background:var(--nav-bg);width:100%;position:static;display:flex;border-top:1px solid #e8eef3;}
.nav-container{width:100%;max-width:1200px;margin:0 auto;display:flex;flex-direction:row;justify-content:center;align-items:center;padding:8px 20px;gap:0;flex-wrap:wrap;}
.nav-container a{color:#3a4a5a;text-decoration:none;font-weight:600;font-size:0.9rem;padding:8px 16px;border-radius:30px;transition:all 0.3s ease;white-space:nowrap;}
.nav-container a:hover{background:#e3f1f9;color:var(--primary);}
.hamburger-menu{display:none;}
.mobile-mask{display:none;}
.mobile-nav-buttons{display:none;}
.site-footer{background:#0d1b2a;color:#FFFFFF;padding:48px 20px 24px;}
.footer-container{max-width:1200px;margin:0 auto;display:grid;grid-template-columns:1.5fr 1fr 1fr;gap:40px;padding-bottom:32px;}
.footer-column h3{color:var(--primary);font-size:1.1rem;font-weight:700;margin-bottom:18px;}
.footer-logo{color:#f7fafc;font-size:1.6rem;font-weight:800;text-transform:uppercase;margin-bottom:12px;}
.footer-column p{color:#cbd5e0;line-height:1.6;font-size:0.92rem;margin:0;}
.footer-nav{display:flex;flex-direction:column;gap:10px;}
.footer-nav a{color:#cbd5e0;text-decoration:none;font-weight:500;font-size:0.9rem;transition:color 0.3s ease;}
.footer-nav a:hover{color:var(--primary);}
.footer-copyright{border-top:1px solid rgba(255,255,255,0.1);padding-top:20px;text-align:center;}
.footer-copyright p{color:#a0aec0;font-size:0.85rem;margin:0;}
@media (max-width:768px){
  :root{--header-offset:108px;}
  .site-header{min-height:108px;}
  .header-container{width:100%;max-width:none;padding:10px 15px;justify-content:center;position:relative;}
  .logo{font-size:1.2rem;margin:0 auto;display:block;}
  .desktop-nav-buttons{display:none;}
  .main-nav{display:none;position:fixed;top:0;right:0;height:100vh;width:75%;max-width:300px;background:var(--nav-bg);flex-direction:column;justify-content:flex-start;z-index:1002;transform:translateX(100%);transition:transform 0.3s ease;box-shadow:-4px 0 20px rgba(0,0,0,0.2);overflow-y:auto;border-top:none;padding-top:60px;}
  .main-nav.active{display:block;transform:translateX(0);}
  .nav-container{flex-direction:column;width:100%;max-width:none;padding:10px;align-items:flex-start;justify-content:flex-start;}
  .nav-container a{display:block;width:90%;padding:12px 15px;border-radius:10px;font-size:1rem;text-align:left;}
  .hamburger-menu{display:flex;position:fixed;top:10px;left:15px;flex-direction:column;justify-content:space-around;width:40px;height:40px;background:transparent;border:none;cursor:pointer;z-index:1003;}
  .hamburger-menu span{display:block;width:25px;height:3px;background:#ffffff;border-radius:2px;margin:3px auto;transition:all 0.3s ease;}
  .hamburger-menu.active span:nth-child(1){transform:translateY(8px) rotate(45deg);}
  .hamburger-menu.active span:nth-child(2){opacity:0;}
  .hamburger-menu.active span:nth-child(3){transform:translateY(-8px) rotate(-45deg);}
  .mobile-mask{display:none;position:fixed;top:0;left:0;width:100%;height:100%;background-color:rgba(0,0,0,0.5);z-index:1001;opacity:0;transition:opacity 0.3s ease;}
  .mobile-mask.active{display:block;opacity:1;}
  .mobile-nav-buttons{display:flex;gap:10px;justify-content:center;padding:8px 15px;width:100%;background:var(--header-top-bg);border:none;z-index:1000;position:relative;}
  .mobile-nav-buttons .btn{padding:8px 18px;font-size:0.85rem;}
  .site-footer{padding:30px 15px 20px;}
  .footer-container{grid-template-columns:1fr;gap:24px;}
}
.page-content img{max-width:100%!important;height:auto!important;display:block;}
.page-content{overflow-x:hidden;max-width:100%;}
body{overflow-x:hidden;}
.page-content,.page-lession,.page-category{padding-top:10px;}
/* 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;
}