/* ===== 全局重置 & 变量 ===== */
:root {
    --primary: #1a73e8;
    --primary-dark: #1557b0;
    --primary-light: #4a9eff;
    --accent: #ff6b35;
    --bg: #f8f9fa;
    --card-bg: #ffffff;
    --text: #1a1a2e;
    --text-light: #6c757d;
    --border: #e9ecef;
    --shadow: 0 4px 20px rgba(0,0,0,0.08);
    --shadow-hover: 0 8px 30px rgba(0,0,0,0.15);
    --radius: 16px;
    --radius-sm: 8px;
    --transition: all 0.3s cubic-bezier(0.4,0,0.2,1);
    --glass-bg: rgba(255,255,255,0.7);
    --glass-border: rgba(255,255,255,0.3);
    --glass-shadow: 0 8px 32px rgba(0,0,0,0.1);
    --nav-height: 70px;
    --max-width: 1200px;
    --font: 'Segoe UI','PingFang SC','Microsoft YaHei',sans-serif;
}
*, *::before, *::after { box-sizing: border-box; margin:0; padding:0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
    font-family: var(--font);
    color: var(--text);
    background: var(--bg);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background 0.3s, color 0.3s;
}
.dark-mode {
    --bg: #0f0f1a;
    --card-bg: #1a1a2e;
    --text: #e0e0e0;
    --text-light: #a0a0b0;
    --border: #2a2a3e;
    --shadow: 0 4px 20px rgba(0,0,0,0.3);
    --shadow-hover: 0 8px 30px rgba(0,0,0,0.5);
    --glass-bg: rgba(26,26,46,0.7);
    --glass-border: rgba(255,255,255,0.1);
    --glass-shadow: 0 8px 32px rgba(0,0,0,0.4);
}
a { color: var(--primary); text-decoration: none; transition: var(--transition); }
a:hover { color: var(--primary-dark); }
img, svg { max-width: 100%; height: auto; display: block; }
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 20px; }
.section { padding: 80px 0; }
.section-title {
    font-size: 2.2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 12px;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.section-subtitle {
    text-align: center;
    color: var(--text-light);
    font-size: 1.1rem;
    margin-bottom: 50px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}
.card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 30px;
    transition: var(--transition);
    border: 1px solid var(--border);
}
.card:hover {
    box-shadow: var(--shadow-hover);
    transform: translateY(-4px);
}
.glass {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius);
    box-shadow: var(--glass-shadow);
}
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: 50px;
    font-weight: 600;
    font-size: 1rem;
    border: none;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    color: #fff;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
}
.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(26,115,232,0.4);
    color: #fff;
}
.btn-accent { background: linear-gradient(135deg, var(--accent), #ff8c42); }
.btn-accent:hover { box-shadow: 0 8px 25px rgba(255,107,53,0.4); }
.btn-outline {
    background: transparent;
    border: 2px solid var(--primary);
    color: var(--primary);
}
.btn-outline:hover {
    background: var(--primary);
    color: #fff;
    box-shadow: 0 8px 25px rgba(26,115,232,0.3);
}
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 30px; }
.grid-3 { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 30px; }
.grid-4 { display: grid; grid-template-columns: 1fr 1fr 1fr 1fr; gap: 24px; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.flex-between { display: flex; align-items: center; justify-content: space-between; }
.text-center { text-align: center; }
.mt-20 { margin-top: 20px; }
.mb-20 { margin-bottom: 20px; }

/* ===== 滚动动画 ===== */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ===== 导航栏 ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: var(--nav-height);
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 100%;
    border-bottom: 1px solid var(--border);
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius);
    box-shadow: var(--glass-shadow);
    border-bottom-left-radius: 0;
    border-bottom-right-radius: 0;
}
.navbar nav {
    display: flex;
    align-items: center;
    gap: 20px;
}
.navbar nav a {
    color: var(--text);
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition);
}
.navbar nav a:hover {
    color: var(--primary);
}

/* ===== 返回顶部 ===== */
#backToTop {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--primary);
    color: #fff;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 999;
    transition: var(--transition);
}
#backToTop:hover {
    transform: scale(1.1);
    box-shadow: 0 6px 20px rgba(0,0,0,0.3);
}

/* ===== 搜索模态 ===== */
#searchModal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.5);
    z-index: 2000;
    align-items: center;
    justify-content: center;
}
#searchModal .card {
    width: 90%;
    max-width: 500px;
    padding: 30px;
}

/* ===== 主题切换按钮 ===== */
#themeToggle {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 50%;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.2rem;
    transition: var(--transition);
}
#themeToggle:hover {
    transform: rotate(180deg);
}

/* ===== 移动菜单 ===== */
#mobileMenuBtn {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 4px;
}

/* ===== FAQ ===== */
.faq-item {
    margin-bottom: 12px;
    cursor: pointer;
}
.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 600;
    font-size: 1.05rem;
}
.faq-icon {
    font-size: 1.2rem;
    transition: transform 0.3s;
}
.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
    color: var(--text-light);
    font-size: 0.95rem;
}

/* ===== 数据展示 ===== */
.counter {
    font-size: 2.5rem;
    font-weight: 800;
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    .section { padding: 50px 0; }
    .section-title { font-size: 1.8rem; }
    .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; gap: 20px; }
    .container { padding: 0 16px; }
    .navbar nav {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--card-bg);
        padding: 20px;
        box-shadow: var(--shadow);
    }
    #mobileMenuBtn { display: block; }
    #backToTop {
        bottom: 20px;
        right: 20px;
        width: 44px;
        height: 44px;
        font-size: 1.2rem;
    }
}

/* ===== 其他微调 ===== */
/* 渐变Banner背景 */
#home {
    background: linear-gradient(135deg, #e8f0fe 0%, #f3e8ff 100%);
    position: relative;
    overflow: hidden;
}
/* 圆角卡片已全局定义 */
/* 毛玻璃效果已全局定义 */
/* 暗色模式已全局定义 */
/* 滚动动画已全局定义 */
/* hover动画已全局定义 */

/* 确保所有内联样式被覆盖或保留 */
/* 注意：HTML中内联样式优先级高于CSS，但此处CSS作为备用或统一 */
/* 由于要求输出完整CSS，上述已包含所有必要样式 */