/* --------------------------
   1. 全局基础重置与排版
   -------------------------- */
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background: linear-gradient(135deg, #ff9d6c 0%, #ffd26f 100%);
    min-height: 100vh;
    color: #333;
    overflow-x: hidden;
}

/* 页面加载动画占位 */
body { opacity: 0; transition: opacity 0.5s ease; }
body.loaded { opacity: 1; }

/* 页面切换 Loading 遮罩 */
.page-transition-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #ff9d6c 0%, #ffd26f 100%);
    z-index: 9999;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 1;
    transition: opacity 0.4s ease, visibility 0.4s ease;
    visibility: visible;
}
.page-transition-overlay.hidden {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}
.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}

/* --------------------------
   2. 背景动画与浮动元素
   -------------------------- */
.bg-animation { position: fixed; top: 0; left: 0; width: 100%; height: 100%; z-index: -1; overflow: hidden; }
.bg-animation::before { content: ''; position: absolute; top: -50%; left: -50%; width: 200%; height: 200%; background: radial-gradient(circle, rgba(255,255,255,0.1) 1px, transparent 1px); background-size: 50px 50px; animation: bgMove 20s linear infinite; }
@keyframes bgMove { 0% { transform: translate(0, 0); } 100% { transform: translate(50px, 50px); } }

.floating-element { position: absolute; background: rgba(255, 255, 255, 0.1); border-radius: 50%; animation: float 6s ease-in-out infinite; }
.floating-element:nth-child(1) { width: 80px; height: 80px; top: 20%; left: 10%; animation-delay: 0s; }
.floating-element:nth-child(2) { width: 120px; height: 120px; top: 60%; right: 10%; animation-delay: 2s; }
.floating-element:nth-child(3) { width: 60px; height: 60px; bottom: 20%; left: 20%; animation-delay: 4s; }
@keyframes float { 0%, 100% { transform: translateY(0) rotate(0deg); } 50% { transform: translateY(-20px) rotate(180deg); } }

/* --------------------------
   3. 通用导航栏 (Navbar)
   -------------------------- */
.navbar { background: rgba(255, 255, 255, 0.95); backdrop-filter: blur(10px); padding: 15px 30px; border-radius: 50px; box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1); display: flex; justify-content: space-between; align-items: center; margin-bottom: 40px; animation: slideDown 0.6s ease-out; transition: all 0.3s ease; }
@keyframes slideDown { from { transform: translateY(-100px); opacity: 0; } to { transform: translateY(0); opacity: 1; } }
.logo { font-size: var(--font-size-lvl-2, 24px); font-weight: bold; background: linear-gradient(45deg, #ff6b35, #f7931e); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.nav-links { display: flex; gap: 30px; list-style: none; }
.nav-links a { text-decoration: none; color: #666; font-size: var(--font-size-lvl-4, 16px); font-weight: 500; transition: all 0.3s ease; position: relative; }
.nav-links a:hover, .nav-links a.active { color: #ff6b35; transform: translateY(-2px); }
.nav-links a::after { content: ''; position: absolute; bottom: -5px; left: 0; width: 0; height: 2px; background: #ff6b35; transition: width 0.3s ease; }
.nav-links a:hover::after, .nav-links a.active::after { width: 100%; }

@media (max-width: 768px) {
    .navbar { margin-bottom: 20px; padding: 10px 20px; }
    .nav-links { display: none; }
}

/* --------------------------
   4. 通用排版与组件
   -------------------------- */
@keyframes fadeInUp { from { transform: translateY(30px); opacity: 0; } to { transform: translateY(0); opacity: 1; } }

.container { max-width: 1200px; margin: 0 auto; padding: 20px; }
.main-content { text-align: center; padding: 60px 0; }

@media (max-width: 768px) {
    .main-content { padding: 20px 0; }
}